Uniplanar bone anchor system

ABSTRACT

The present teachings provide one or more surgical implements for repairing damaged tissue, such as in the case of a spinal fixation procedure. A uniplanar bone anchor system for a fixation procedure is provided. The system can include a bone fastener including a head with a bearing surface and a shaft adapted to engage an anatomy. The system can also include a saddle, which can include a first bore formed about a longitudinal axis that receives the bone fastener and a coupling bore defined transverse to the longitudinal axis. The system can also include a coupling system, which can have a second bearing surface. The coupling system can be received through the coupling bore such that the second bearing surface of the coupling system can contact the bearing surface to permit the bone fastener to move in only one plane.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/169,200 filed on Jan. 31, 2014, now issued as U.S. Pat. No. 9,211,143which is a divisional of U.S. patent application Ser. No. 12/842,556filed on Jul. 23, 2010, now issued as U.S. Pat. No. 8,647,370, which isa continuation-in-part of U.S. patent application Ser. No. 12/688,013filed on Jan. 15, 2010, now issued as U.S. Pat. No. 8,419,778. Thedisclosures of the above applications are incorporated herein byreference.

INTRODUCTION

In general, the human musculoskeletal system is composed of a variety oftissues including bone, ligaments, cartilage, muscle, and tendons.Tissue damage or deformity stemming from trauma, pathologicaldegeneration, or congenital conditions often necessitates surgicalintervention to restore function. Surgical intervention can include anysurgical procedure that can restore function to the damaged or deformedtissue, which can require the use of one or more orthopedic prosthesis,such as orthopedic nails, screws, implants, etc., to restore function tothe damaged tissue.

Generally, in order to stabilize various boney tissue relative to oneanother, such as vertebrae of the spine, one or more implants can becoupled to each of the vertebrae and interconnected via a suitabledevice. In one example, implants or anchors can be coupled to each ofthe vertebrae, and a connecting device, such as a rod, can be coupled toeach of the anchors to stabilize or fix the vertebrae relative to eachother. In certain instances, it may be desirable to provide an anchorthat can move relative to the connecting device. The present teachingscan provide an anchor for use in repairing damaged or deformed tissue,such as a bone anchor that can be movable in only one plane for use in afixation procedure.

Provided is a uniplanar bone anchor system for a fixation procedure. Thesystem can include a bone fastener including a head and a shaft adaptedto engage an anatomy. The head can have a bearing surface. The systemcan also include a saddle, which can extend along a longitudinal axis.The saddle can have a proximal end and a distal end. The distal end ofthe saddle can include a first bore formed about the longitudinal axisthat receives the head of the bone fastener and at least one couplingbore defined transverse to the longitudinal axis through at least aportion of the distal end. The at least one coupling bore can be incommunication with the first bore. The system can also include acoupling system, which can have at least one second bearing surface. Thecoupling system can be received through the at least one coupling boresuch that the at least one second bearing surface of the coupling systemcan contact the bearing surface of the head to permit the bone fastenerto move relative to the saddle in only one plane.

Further provided is a uniplanar bone anchor system for a fixationprocedure. The system can include a bone fastener including a head and ashaft adapted to engage an anatomy. The head can have at least one firstbearing surface. The system can also include a saddle having a proximalend and a distal end. The distal end of the saddle can include a firstbore formed about the longitudinal axis, which can receive the head ofthe bone fastener. The system can comprise a coupling system, which caninclude a cap and at least one annular support. The cap can define atleast one second bearing surface configured to allow the bone fastenerto move in one plane relative to the saddle. The at least one annularsupport can be coupled to the head of the bone fastener to retain thebone fastener within the first bore. The cap can be received within thefirst bore such that the at least one second bearing surface of the capcontacts the at least one first bearing surface of the head to permitthe bone fastener to move relative to the saddle in one plane.

Also provided is a uniplanar bone anchor system for a fixationprocedure. The system can include a bone fastener having a head and ashaft adapted to engage an anatomy. The head can have a first bearingsurface opposite a second bearing surface. The system can also include asaddle extending along a longitudinal axis. The saddle can have aproximal end and a distal end. The distal end can include a first boreformed about the longitudinal axis that receives the head of the bonefastener. The distal end can also include a first sidewall opposite asecond sidewall. A first coupling bore can be defined transverse to thelongitudinal axis through at least a portion of the distal end. A secondcoupling bore can be defined transverse to the longitudinal axis throughat least a portion of the distal end. The first coupling bore and thesecond coupling bore can be spaced a distance apart from each other andin communication with the first bore. The system can also include afirst coupling pin, which can be positionable within the first couplingbore. The first coupling pin can define a third bearing surface incommunication with the first bore. The system can include a secondcoupling pin. The second coupling pin can be positionable within thesecond coupling bore, and can define a fourth bearing surface incommunication with the second bore. The bone fastener can be receivedwithin the first bore such that the first bearing surface of the headcan contact the third bearing surface of the first coupling pin, and thesecond bearing surface of the head can contact the fourth bearingsurface of the second coupling pin to enable the bone fastener toarticulate relative to the saddle in a single plane.

According to various aspects, also provided is a uniplanar bone anchorsystem for a fixation procedure. The system can include a bone fastenerincluding a head and a shaft adapted to engage an anatomy. The head canhave at least one first bearing surface and at least one firstengagement surface adjacent to the at least one first bearing surface.The system can also include a saddle extending along a longitudinalaxis. The saddle can have a first bore that receives the head of thebone fastener and at least one coupling bore defined transverse to thelongitudinal axis and in communication with the first bore. The systemcan include a pressure cap received within the first bore and having asecond engagement surface in contact with the at least one firstengagement surface of the head of the bone fastener. The system canfurther include a coupling system having at least one second bearingsurface. The coupling system can be received through the at least onecoupling bore such that the at least one second bearing surface of thecoupling system can contact the at least one first bearing surface ofthe head and the contact between the at least one first engagementsurface of the head and the at least one second engagement surface ofthe pressure cap permits the bone fastener to move relative to thesaddle in only one plane.

Further provided is a uniplanar bone anchor system for a fixationprocedure. The system can include a bone fastener. The bone fastener caninclude a head and a shaft adapted to engage an anatomy. The head canhave a first engagement surface opposite a second engagement surface.The system can comprise a saddle extending along a longitudinal axis.The saddle can have a first bore that receives the head of the bonefastener, a first coupling bore in communication with the first bore anda second coupling bore in communication with the first bore. The systemcan also comprise a pressure cap received within the first bore adjacentto the head of the bone fastener. The pressure cap can have a thirdengagement surface in contact with the first engagement surface and thesecond engagement surface of the head of the bone fastener. The systemcan also include a coupling system received through each of the firstcoupling bore and the second coupling bore that cooperates with thefirst engagement surface, second engagement surface and third engagementsurface to permit the bone fastener to move relative to the saddle inonly one plane.

Additionally, provided is a uniplanar bone anchor system for a fixationprocedure. The system can include a bone fastener. The bone fastener caninclude a head and a shaft adapted to engage an anatomy. The head canhave a first engagement surface opposite a second engagement surface, afirst bearing surface adjacent to the first engagement surface andopposite a second bearing surface. The second bearing surface can beadjacent to the second engagement surface. The head of the bone fastenercan also include a first planar surface opposite a second planarsurface. The first planar surface can be defined between the firstbearing surface and the second bearing surface. The system can comprisea saddle, which can extend along a longitudinal axis. The saddle canhave a first bore with an upper portion and a lower portion for receiptof the head of the bone fastener. The saddle can also have a firstcoupling bore in communication with the lower portion of the first boreand a second coupling bore in communication with the lower portion ofthe first bore. The first coupling bore and second coupling bore can beformed transverse to the longitudinal axis and spaced apart from eachother. The system can comprise a pressure cap received within the upperportion of the first bore adjacent to the head of the bone fastener. Thepressure cap can have a plurality of teeth in contact with the firstengagement surface and the second engagement surface of the head of thebone fastener. The system can also include a coupling system receivedthrough each of the first coupling bore and the second coupling bore andin communication with each of the first bearing surface and the secondbearing surface to enable the bone fastener to move relative to thesaddle in only one plane.

Further areas of applicability will become apparent from the descriptionprovided herein. It should be understood that the description andspecific examples are intended for purposes of illustration only and arenot intended to limit the scope of the present teachings.

DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present teachings in any way.

FIG. 1 is a schematic environmental illustration of an exemplaryuniplanar bone anchor system for use with a connecting device in afixation procedure according to the present teachings;

FIG. 2 is a schematic cross-sectional illustration of the uniplanar boneanchor system of FIG. 1;

FIG. 3 is a perspective view of the uniplanar bone anchor system of FIG.1;

FIG. 4 is an exploded view of the uniplanar bone anchor system of FIG.1.

FIG. 5 is a perspective view of an exemplary saddle for use with theuniplanar bone anchor system of FIG. 1;

FIG. 6 is a schematic, cross-sectional illustration of the uniplanarbone anchor system, taken along line 6-6 of FIG. 3, which illustrates afirst direction of uniplanar motion for the uniplanar bone anchorsystem;

FIG. 7 is a schematic, cross-sectional illustration of the uniplanarbone anchor system, taken along line 6-6 of FIG. 3, which illustrates aneutral position for the uniplanar bone anchor system;

FIG. 8 is a schematic, cross-sectional illustration of the uniplanarbone anchor system, taken along line 6-6 of FIG. 3, which illustrates asecond direction of uniplanar motion for the uniplanar bone anchorsystem;

FIG. 9 is a schematic cross-sectional illustration of another exemplaryuniplanar bone anchor system for use with a connecting device in afixation procedure according to the present teachings;

FIG. 10 is a perspective view of the uniplanar bone anchor system ofFIG. 9;

FIG. 11 is a perspective view of an exemplary pressure cap for use withthe uniplanar bone anchor system of FIG. 9;

FIG. 12 is a schematic perspective illustration of another exemplaryuniplanar bone anchor system for use with a connecting device in afixation procedure according to the present teachings;

FIG. 13 is a schematic, cross-sectional illustration of the uniplanarbone anchor system, taken along line 13-13 of FIG. 12, which illustratesa first direction of uniplanar motion for the uniplanar bone anchorsystem;

FIG. 14 is a schematic, cross-sectional illustration of the uniplanarbone anchor system, taken along line 13-13 of FIG. 12, which illustratesa neutral position for the uniplanar bone anchor system;

FIG. 15 is a schematic, cross-sectional illustration of the uniplanarbone anchor system, taken along line 13-13 of FIG. 12, which illustratesa second direction of uniplanar motion for the uniplanar bone anchorsystem;

FIG. 16 is a schematic partial cross-sectional illustration of anotherexemplary uniplanar bone anchor system for use with a connecting devicein a fixation procedure according to the present teachings;

FIG. 17 is a schematic perspective illustration the uniplanar boneanchor system of FIG. 16;

FIG. 18 is an exploded view of the uniplanar bone anchor system of FIG.16;

FIG. 19 is a perspective view of an exemplary saddle for use with theuniplanar bone anchor system of FIG. 16;

FIG. 20 is a schematic, cross-sectional illustration of the uniplanarbone anchor system, taken along line 20-20 of FIG. 17, which illustratesa first direction of uniplanar motion for the uniplanar bone anchorsystem;

FIG. 21 is a schematic, cross-sectional illustration of the uniplanarbone anchor system, taken along line 20-20 of FIG. 17, which illustratesa neutral position for the uniplanar bone anchor system;

FIG. 22 is a schematic, cross-sectional illustration of the uniplanarbone anchor system, taken along line 20-20 of FIG. 17, which illustratesa second direction of uniplanar motion for the uniplanar bone anchorsystem;

FIG. 23 is a schematic, cross-sectional illustration of the uniplanarbone anchor system, taken along line 23-23 of FIG. 17;

FIG. 24 is a schematic cross-sectional illustration of another exemplaryuniplanar bone anchor system, similar to the uniplanar bone anchorsystem of FIGS. 16-23, for use with a connecting device in a fixationprocedure according to the present teachings;

FIG. 25 is a schematic perspective illustration of another exemplaryuniplanar bone anchor system for use with a connecting device in afixation procedure according to the present teachings;

FIG. 26 is an exploded view of the uniplanar bone anchor system of FIG.25;

FIG. 27 is a perspective view of an exemplary saddle for use with theuniplanar bone anchor system of FIG. 25;

FIG. 28 is a perspective view of an exemplary cap for use with theuniplanar bone anchor system of FIG. 25;

FIG. 28A is a perspective view of a bottom surface of the cap of FIG.28;

FIG. 29 is a perspective view of an exemplary support for use with theuniplanar bone anchor system of FIG. 25;

FIG. 30 is a schematic, cross-sectional illustration of the uniplanarbone anchor system, taken along line 30-30 of FIG. 25, which illustratesa range of uniplanar motion for the uniplanar bone anchor system;

FIG. 31 is a schematic cross-sectional illustration of another exemplaryuniplanar bone anchor system for use with a connecting device in afixation procedure according to the present teachings;

FIG. 32 is a perspective view of an exemplary bone fastener for use withthe uniplanar bone anchor system of FIG. 31;

FIG. 33 is a perspective view of an exemplary cap for use with theuniplanar bone anchor system of FIG. 31;

FIG. 34 is a perspective view of a bottom surface of the cap of FIG. 33;

FIG. 35 is a schematic, cross-sectional illustration of the uniplanarbone anchor system, which illustrates a range of uniplanar motion forthe uniplanar bone anchor system of FIG. 31;

FIG. 36 is a schematic perspective illustration of an exemplaryuniplanar bone anchor system having a selectable single plane of motionfor use with a connecting device in a fixation procedure according tothe present teachings;

FIG. 37 is an exploded view of the uniplanar bone anchor system of FIG.36;

FIG. 38 is a perspective view of an exemplary saddle for use with theuniplanar bone anchor system of FIG. 36;

FIG. 39 is a perspective view of an exemplary cap for use with theuniplanar bone anchor system of FIG. 36;

FIG. 40 is an exploded, perspective view of another exemplary lockingmember and cap for use with the uniplanar bone anchor system of FIG. 36;

FIG. 41 is an exploded, perspective view of another exemplary lockingmember and cap for use with the uniplanar bone anchor system of FIG. 36;

FIG. 42 is a schematic, cross-sectional illustration of the uniplanarbone anchor system of FIG. 36, which illustrates the locking member in afirst, unlocked position to enable the selection of a desired singleplane of motion;

FIG. 43 is a schematic, cross-sectional illustration of the uniplanarbone anchor system of FIG. 36, which illustrates the locking member in asecond, locked position;

FIG. 44 is a schematic cross-sectional illustration of another exemplaryuniplanar bone anchor system for use with a connecting device in afixation procedure according to the present teachings;

FIG. 45 is a perspective view of an exemplary cap for use with theuniplanar bone anchor system of FIG. 44;

FIG. 46 is a perspective view of an exemplary locking member for usewith the uniplanar bone anchor system of FIG. 44;

FIG. 47 is another exemplary pressure cap for use with any of theexemplary bone anchor systems;

FIG. 48 is schematic cross-sectional illustration of another exemplaryuniplanar bone anchor system for use with a connecting device in afixation procedure according to the present teachings;

FIG. 49 is a perspective illustration of another exemplary uniplanarbone anchor system for use with a connecting device in a fixationprocedure according to the present teachings;

FIG. 50 is an exploded view of the uniplanar bone anchor system of FIG.49;

FIG. 51 is a schematic, cross-sectional illustration of the uniplanarbone anchor system, taken along line 51-51 of FIG. 49, which illustratesa non-motion direction for the uniplanar bone anchor system;

FIG. 52 is a schematic, cross-sectional illustration of the uniplanarbone anchor system, taken along line 53-53 of FIG. 49, which illustratesa first direction of uniplanar motion for the uniplanar bone anchorsystem;

FIG. 53 is a schematic, cross-sectional illustration of the uniplanarbone anchor system, taken along line 53-53 of FIG. 49, which illustratesa neutral position for the uniplanar bone anchor system; and

FIG. 54 is a schematic, cross-sectional illustration of the uniplanarbone anchor system, taken along line 53-53 of FIG. 49, which illustratesa second direction of uniplanar motion for the uniplanar bone anchorsystem.

DESCRIPTION OF VARIOUS ASPECTS

The following description is merely exemplary in nature and is notintended to limit the present teachings, application, or uses. It shouldbe understood that throughout the drawings, corresponding referencenumerals indicate like or corresponding parts and features. Although thefollowing description is related generally to a system for use in ananatomy to repair damaged tissue, such as in the case of spinal fusion,static spinal stabilization or dynamic spinal stabilization, it will beunderstood that the system as described and claimed herein can be usedin any appropriate surgical procedure, such as in a minimally invasiveorthopedic alignment or fixation procedure. Therefore, it will beunderstood that the following discussions are not intended to limit thescope of the present teachings and claims herein.

With reference to FIGS. 1-11, a uniplanar bone anchor system 10 isshown. The bone anchor system 10 may be particularly adapted for spinalfixation procedures. Various aspects of the present teachings, however,may have application for other procedures. In certain applications, thebone anchor system 10 can be coupled to one or more vertebrae orvertebral bodies V in a lumbar region of the spine, however, the boneanchor system 10 can be used in other anatomical locations. The boneanchor system 10 can include a tulip head or saddle 12 and a boneengaging member or bone fastener 14, which can be coupled together via auniplanar coupling system 16. The uniplanar coupling system 16 canenable the saddle 12 to move relative to the bone fastener 14 in only asingle plane. The bone anchor system 10 can also include a pressure cap17 (FIGS. 9-11), if desired.

As will be discussed in greater detail herein, the saddle 12 can beconfigured to receive a connecting device or rod 18, which can be usedto interconnect multiple bone anchor systems 10 (the same or differenttypes) in an exemplary spinal fixation procedure. It should be noted,however, that although the bone anchor system 10 is generallyillustrated and described herein a single assembly for use with a singleconnecting rod 18, any combination of bone anchor systems 10 andconnecting rods 18 can be employed during a surgical procedure.

For example, in a single level spinal fixation procedure, two boneanchor systems 10 can receive a single connecting rod 18. A multiplelevel spinal fixation procedure, however, will generally requireadditional bone anchor systems 10, which can include other types of boneanchor systems, such as those employing non-movable bone fasteners. Inaddition, the bone anchor systems 10 need not be coupled to adjacentvertebral bodies V, but rather, the bone anchor systems 10 can bepositioned so as to skip adjacent vertebral bodies V, if desired.

With reference to FIGS. 3-8, the saddle 12 can be substantially U-shapedand symmetrical with respect to a longitudinal axis L defined by thebone anchor system 10. The saddle 12 can include a first or proximal end20 and a second or distal end 22. In one example, the proximal end 20can be integrally formed with the distal end 22 out of a suitablebiocompatible material, however, the proximal end 20 and distal end 22can be formed and coupled together through any suitable processingtechnique, such as machining and welding, etc. The proximal end 20 caninclude a first arm 24 and a second arm 26. The first arm 24 and secondarm 26 can extend upwardly from the distal end 22 to define the U-shape.Each of the first arm 24 and the second arm 26 can include an insertionfeature 28 and a mating portion 30.

The insertion feature 28 can enable the saddle 12 to be releasablycoupled to a suitable instrument or tool for inserting and coupling thebone anchor system 10 to the anatomy. In one example, the insertionfeature 28 can comprise a notch or groove formed on an exterior surface24 a, 26 a of each of the first arm 24 and second arm 26. It should benoted, however, that the proximal end 20 can have any suitableconfiguration to engage a tool, such as keyed portions, chamfers, etc.Further, it should be noted that particular tools for use with the boneanchor system 10 are beyond the scope of the present teachings and neednot be described herein. In a conventional manner insofar as the presentteachings are concerned, various tools can be used to connect the boneanchor system 10 to a respective vertebral body V. Exemplary tools caninclude those employed in the Polaris™ 5.5 Spinal System, commerciallyavailable from Biomet, Inc. of Warsaw, Ind., or the tools disclosed incommonly owned U.S. Patent Publication No. 2008/0077138, filed on Apr.20, 2007 and incorporated by reference herein.

The mating portion 30 can be configured to receive a fastening mechanismto couple or retain the connecting rod 18 within the saddle 12. Forexample, the mating portion 30 can comprise a plurality of threads,which can be formed on an interior surface 24 b, 26 b of each of thefirst arm 24 and second arm 26. In this example, the mating portion 30can matingly engage threads formed on a set screw 32 to retain theconnecting rod 18 within the saddle 12 (FIG. 2). It should be noted,however, that the proximal end 20 can have any suitable configuration toretain the connecting rod 18 to the saddle 12, such as keyed portions,teeth, etc.

With reference to FIGS. 3-8, the distal end 22 can be generallyrectangular, and can include a first, top or a receiver surface 22 a anda second or bottom surface 22 b. It should be noted, however, that thedistal end 22 can have any desired shape such as circular, octagonal,etc. In addition, the distal end 22 can include a central aperture orcentral bore 36 and at least one or more coupling apertures or couplingbores 38. The receiver surface 22 a can provide clearance for theassembly of the connecting rod 18 to the saddle 12, but does notgenerally contact the connecting rod 18. In one example, the receiversurface 22 a can comprise a generally arcuate, concave surface thatforms the U-shape of the saddle 12, however, the receiver surface 22 acan comprise any desired shape, such as square, etc.

The central bore 36 can be defined through the distal end 22 from thereceiver surface 22 a to the bottom surface 22 b. Generally, the centralbore 36 can be sized to receive the bone fastener 14, and can cooperatewith the coupling system 16 to allow the bone fastener 14 to move inonly one plane. With reference to FIGS. 5-8, the central bore 36 caninclude a first sidewall 42, a second sidewall 44, a third sidewall 46and a fourth sidewall 48. Generally, the first sidewall 42 can beopposite and substantially identical to the third sidewall 46, while thesecond sidewall 44 can be opposite and substantially identical to thefourth sidewall 48.

In one example, with reference to FIGS. 6-8, the second sidewall 44 andthe fourth sidewall 48 can be substantially smooth or planar. The firstsidewall 42 and third sidewall 46 can each include a limiting projectionor lip 50 and a channel 52. The lip 50 can be formed adjacent to thereceiver surface 22 a. Each lip 50 can extend along the respective oneof the first sidewall 42 and third sidewall 46 from the second sidewall44 to the fourth sidewall 48. Generally, each lip 50 can extendoutwardly from the respective one of the first sidewall 42 and thirdsidewall 46. A size of a width of the lip 50 can be used to control orlimit the range of uniplanar motion of the bone fastener 14.

The channel 52 can be formed adjacent to or near the bottom surface 22b. Each channel 52 can be in communication with a respective one of thecoupling bores 38, and can define a passageway for receipt of a portionof the coupling system 16, as will be discussed. Each channel 52 can bedefined along the respective one of the first sidewall 42 and thirdsidewall 46 from the second sidewall 44 to the fourth sidewall 48. Eachchannel 52 can be substantially cylindrical, and in one example, eachchannel 52 can be circumferentially open along a length of the channel52 that extends from the second sidewall 44 to the fourth sidewall 48(FIG. 4). Generally, the channel 52 can be circumferentially open toenable the coupling system 16 to contact a portion of the bone fastener14, as will be discussed.

The coupling bores 38 can be sized to receive the coupling system 16therein. In one example, the coupling bores 38 can be annular, and canbe formed adjacent to the bottom surface 22 b of the distal end 22. Thecoupling bores 38 can be defined through the second sidewall 44 and thefourth sidewall 48. Generally, the coupling system 16 can be press-fitinto the coupling bores 38, however, any suitable technique could beused to couple the coupling system 16 to the distal end 22 of the saddle12, such as adhesives, welding, etc. Thus, the coupling bores 38 canhave any desired shape to mate with the coupling system 16, such assquare, keyed, etc. The coupling bores 38 can cooperate with thecoupling system 16 to enable the bone fastener 14 to move in only oneplane, as will be discussed further herein.

The bone fastener 14 can be received through the central bore 36 of thesaddle 12, and can be coupled to the saddle 12 via the coupling system16. With reference to FIGS. 4 and 6-8, the bone fastener 14 can includea proximal end or head 56 and a distal end or shaft 58. The head 56 canbe configured to retain the bone fastener 14 within the saddle 12, andcan be coupled to the connecting rod 18. In one example, the head 56 canbe an annular ring, and can have a thickness T. The thickness T can besized to ensure that the head 56 can move in a single plane. Optionally,the head 56 can also include a bore 55, which can be configured toenable the bone fastener 14 to be coupled to a respective vertebral bodyV. In one example, the bore 55 can be threaded, to matingly engage aplurality of threads on a suitable tool, such as a drill. If employed,the bore 55 can cooperate with the tool to align the shaft 58 axiallyduring the insertion of the bone fastener 14 into the anatomy.

The head 56 can define a first bearing surface 56 a, a second bearingsurface 56 b, a first planar surface 56 c and a second planar surface 56d. The first bearing surface 56 a can be generally opposite the secondbearing surface 56 b, and the first planar surface 56 c can be generallyopposite the second planar surface 56 d. The first bearing surface 56 aand the second bearing surface 56 b can be adjacent to the firstsidewall 42 and the third sidewall 46 when the bone fastener 14 ispositioned within the saddle 12. Similarly, the first planar surface 56c and the second planar surface 56 d can be adjacent to the secondsidewall 44 and the fourth sidewall 48 when the bone fastener 14 ispositioned within the saddle 12.

The first bearing surface 56 a and the second bearing surface 56 b canbe in communication with a portion of the coupling system 16 so that thebone fastener 14 can articulate relative to the saddle 12 in one plane.The first planar surface 56 c and the second planar surface 56 d cancooperate with the second sidewall 44 and the fourth sidewall 48 torestrict or prevent the motion of the bone fastener 14 in more than oneplane, as will be discussed herein.

The shaft 58 can be configured to engage the anatomy to secure the bonefastener 14 to the anatomy. In one example, the shaft 58 can include aplurality of threads 58 a, which can couple the bone fastener 14 to adesired vertebral body V. It should be noted that the shaft 58 mayinclude other or additional generally known features to facilitate thecoupling of the bone fastener 14 to the anatomy, such as flutes,grooves, etc.

With reference to FIGS. 4 and 6-8, in one example, the coupling system16 can comprise at least one or more pins 54. The pins 54 can becomposed of any suitable biocompatible material, such as a biocompatiblemetal, metal alloy or polymer. The pins 54 can have a length, which canenable the pins 54 to extend through the second sidewall 44 and thefourth sidewall 48, along the first sidewall 42 and third sidewall 46.The pins 54 can be generally cylindrical, and can each include a bearingsurface 54 a. A respective one of the bearing surfaces 54 a can contactthe first bearing surface 56 a, while the other of the bearing surfaces54 a can contact the second bearing surface 56 b of the bone fastener 14to enable the bone fastener 14 to articulate relative to the couplingsystem 16. In addition, the contact between the pins 54 and the bonefastener 14 can retain the bone fastener 14 within the saddle 12.

With brief reference to FIGS. 9-11, the pressure cap 17 can beoptionally coupled to the head 56 of the bone fastener 14 to furtherdistribute forces across the head 56 of the bone fastener 14. It shouldbe noted that the pressure cap 17 is optional, as the contact betweenthe bone fastener 14 and the connecting rod 18 alone can distributeforces across the head 56 of the bone fastener 14 (FIG. 9). The pressurecap 17 can generally be sized to be positioned within the central bore36 of the saddle 12.

In one example, the pressure cap 17 can be sized such that a first ortop surface 60 of the pressure cap 17 extends slightly above thereceiver surfaces 22 a of the saddle 12 when the pressure cap 17 iscoupled to the saddle 12 (FIG. 10). This can allow the pressure cap 17to apply a force to the head 56 of the bone fastener 14 when theconnecting rod 18 is coupled to the saddle 12 via the set screw 32 (FIG.9). This force applied by the pressure cap 17 can provide for morecontrolled movement of the bone fastener 14 due to the frictional forcesacting between the pressure cap 17 and the bone fastener 14. Inaddition, the use of the pressure cap 17 with the bone fastener 14provides a larger surface area for the distribution of forces acting onthe bone fastener 14. It should be noted, however, that the pressure cap17 could also be sized to enable the pressure cap 17 to be press-fitinto the central bore 36 of the saddle 12 to apply the force to the bonefastener 14, if desired. With reference to FIG. 11, the pressure cap 17can include the top surface 60 opposite a second or bottom surface 62, afirst sidewall 64 opposite a second sidewall 66 and a central bore oraperture 68.

The top surface 60 can define an arcuate or concave groove 60 a, whichcan extend from the first sidewall 64 to the second sidewall 66. Thegroove 60 a can generally be sized to receive a portion of theconnecting rod 18, such that a portion of the connecting rod 18 can besupported by the top surface 60. The bottom surface 62 can be arcuate orconcave, and generally, can be shaped to mate with the head 56 of thebone fastener 14. The bottom surface 62 can be smooth to enable the bonefastener 14 to move relative to the pressure cap 17.

The first sidewall 64 and the second sidewall 66 can each extend fromthe top surface 60 to the bottom surface 62. The first sidewall 64 andthe second sidewall 66 can each include a lip or projection 64 a, 66 a,respectively. With reference to FIG. 9, the projections 64 a, 66 a canbe configured to extend below or under the lips 50 of the first sidewall42 and third sidewall 46 of the central bore 36. The projections 64 a,66 a can cooperate with the lips 50 to retain the pressure cap 17 withinthe central bore 36 of the saddle 12 against the force of gravity whenthe saddle 12 is rotated.

The aperture 68 can be defined about a central axis of the pressure cap17. The aperture 68 can have a diameter, which can be sized to enable asuitable tool to pass through the pressure cap 17 to facilitate couplingthe bone fastener 14 to the anatomy. In one example, the diameter of theaperture 68 can be about as large as or larger than a diameter of thebore 55 formed in the head 56 of the bone fastener 14. It should benoted, however, that in the case of a press-fit pressure cap 17, anaperture 68 need not be provided as the bone fastener 14 could becoupled to the anatomy prior to pressing the pressure cap 17 into thesaddle 12.

With reference to FIGS. 2 and 9, the connecting rod 18 can be coupled toor retained within the saddle 12. The connecting rod 18 can be coupledto the saddle 12 via a suitable mechanical fastener, such as the setscrew 32. An exemplary connecting rod 18 and set screw 32 can besubstantially similar to the connecting rod and set screw employed inthe Polaris™ 5.5 Spinal System, commercially available from Biomet, Inc.of Warsaw, Ind., or the connecting element disclosed in commonly ownedU.S. Patent Publication No. 2008/0077138, filed on Apr. 20, 2007 andpreviously incorporated by reference herein. As the connecting rod 18and the set screw 32 can be generally known, the connecting rod 18 andset screw 32 need not be discussed in great detail herein.

Briefly, however, the connecting rod 18 can comprise an elongated solidcylindrical tube or solid shaft. The connecting rod 18 can also includea slight curvature, which can correspond to the natural curvature of thespine. Typically, the connecting rod 18 can be composed of a suitablebiocompatible material having sufficient rigidity to fix the vertebralbodies V relative to each other. The set screw 32 can include threads,which can matingly engage the threads formed on the mating portion 30 ofthe proximal end 20 of the saddle 12.

The ability of the bone fastener 14 to move in one plane relative to thesaddle 12 can allow the saddle 12 to move in one plane when the bonefastener 14 is fixedly coupled to the anatomy. In turn, this can allowthe surgeon to position the saddle 12 in a desired position relative tothe bone fastener 14 prior to coupling the connecting rod 18 to thesaddle 12 with the set screw 32. As the surgeon tightens the set screw32 onto the connecting rod 18, the connecting rod 18 can be pushed ontothe head 56 of the bone fastener 14 or the pressure cap 17, which cansecure or fix the bone fastener 14 in the desired position relative tothe saddle 12. By allowing the surgeon to select a desired position forthe saddle 12 relative to the bone fastener 14, the surgeon can moreeasily insert the connecting rod 18 into the saddles 12. In addition,the positioning of the saddles 12 prior to the coupling of theconnecting rod 18 can allow for a better alignment of the patient'sspine.

With reference to FIG. 9, in order to assemble the bone anchor system10, the pressure cap 17, if employed, can be positioned in the centralbore 36 of the saddle 12 such that the projections 64 a, 66 a are incontact with the lips 50. Then, the bone fastener 14 can be positionedthrough the central bore 36 of the saddle 12. Next, with reference toFIGS. 6-8, the pins 54 of the coupling system 16 can be inserted orpressed through the coupling bores 38, into the channels 52 of the firstsidewall 42 and third sidewall 46 of the central bore 36. Once thecoupling system 16 is pressed into the saddle 12, the bone fastener 14can be retained in the saddle 12 such that the bone fastener 14 ismovable in only one plane.

In this regard, the first planar surface 56 c and second planar surface56 d of the bone fastener 14 can be in contact with the smooth or planarsecond sidewall 44 and fourth sidewall 48 of the central bore 36,thereby restricting or limiting the motion of the bone fastener 14 to asingle plane, as shown in FIGS. 6-8. The single plane of motion can bedefined by the bearing surfaces 54 a of the pins 54 and the projections64 a, 66 a of the pressure cap 17 or at least one of the lips 50 of thefirst sidewall 42 and third sidewall 46 if the pressure cap 17 is notemployed.

In one example, the bearing surfaces 54 a of the pins 54 can contact thefirst bearing surface 56 a and the second bearing surface 56 b of thebone fastener 14 to enable the bone fastener 14 to articulate relativeto the coupling system 16. The lips 50 of the central bore 36 or theprojections 64 a, 66 a of the pressure cap 17 can limit the articulationof the bone fastener 14 relative to the coupling system 16. As the bonefastener 14 moves or articulates in the single plane, a portion of thefirst bearing surface 56 a and the second bearing surface 56 b of thebone fastener 14 can contact at least one of the lips 50 of the saddle12, thereby preventing further movement or articulation of the bonefastener 14 (FIGS. 6 and 8). Thus, the saddle 12 and the coupling system16 can restrict or limit the motion of the bone fastener 14 to a singleplane.

In this regard, the bone fastener 14 can require about three points ofcontact to allow the motion of the bone fastener 14 to be a singleplane. In one example, the head 56 of the bone fastener 14 can requireabout three points or lines of contact to form a substantially circularpath or single substantially circular plane about which the bonefastener 14 can rotate. For example, the head 56 can contact each of thepins 54 and one of the lips 50; one of the pins 54 and both of the lips50; one of the pins 54, one of the lips 50 and one of the second orfourth sidewalls 44, 48 of the central bore 36, etc.

With the bone fastener 14 coupled to the saddle 12 via the couplingsystem 16, surgical access can be made through the skin adjacent to thevertebral bodies V of interest (FIG. 1). The specific surgical accessapproaches are beyond the scope of the present application, but forexample, surgical access can be obtained via a minimally invasivesurgical procedure such as that used with the Polaris™ 5.5 SpinalSystem, commercially available from Biomet, Inc. of Warsaw, Ind., or theminimally invasive surgical procedure disclosed in commonly owned U.S.Patent Publication No. 2008/0077138, filed on Apr. 20, 2007 andpreviously incorporated by reference herein.

Next, one or more bone anchor systems 10 can be coupled to a respectivevertebral body V via the bone fastener 14. Various techniques can beused to couple the bone anchor systems 10 to the anatomy, such as thosedescribed in commonly owned U.S. Patent Publication No. 2008/0077138,filed on Apr. 20, 2007, previously incorporated by reference herein. Inone example, if each bone fastener 14 includes the bore 55 defined inthe head 56, a suitable tool can be coupled to the bore 55 to align anddrive the bone fastener 14 into the anatomy in a conventional manner.Once the bone anchor systems 10 are coupled to the anatomy, the saddles12 can be moved into a desired position relative to the bone fastener 14by the surgeon. Then, the connecting rod 18 can be inserted into thesaddle 12 of each of the bone anchor systems 10. Generally, theconnecting rod 18 can be inserted such that the connecting rod 18 restson the head 56 of the bone fastener 14 (FIG. 2) and optionally, aportion of the groove 60 a of the pressure cap 17 (FIG. 9).

With the connecting rod 18 positioned in the saddles 12 of the boneanchor systems 10, the set screw 32 can be coupled to each matingportion 30 of each saddle 12 (FIGS. 2 and 9). The coupling of the setscrew 32 can apply a force to the pressure cap 17 to move the groove 60a of the pressure cap 17 substantially adjacent to the receiver surfaces22 a of the saddle 12, if employed. This movement of the pressure cap 17can apply a force to the head 56 of the bone fastener 14, which candistribute forces over the head 56 of the bone fastener 14. The couplingof the set screw 32 to the saddle 12 can couple the connecting rod 18 tothe bone anchor system 10.

As discussed, since the surgeon is able to position the saddles 12relative to the bone fasteners 14 prior to coupling the connecting rod18 to the respective bone anchor system 10, the surgeon can more easilyinsert the connecting rod 18 into the saddles 12. In addition, thepositioning of the saddles 12 prior to the coupling of the connectingrod 18 can allow for a better alignment of the patient's spine.

With reference now to FIGS. 12-15, in one example, a bone anchor system100 can be employed with the connecting rod 18 to repair a damagedportion of an anatomy. As the bone anchor system 100 can be similar tothe bone anchor system 10 described with reference to FIGS. 1-11, onlythe differences between the bone anchor system 10 and the bone anchorsystem 100 will be discussed in great detail herein, and the samereference numerals will be used to denote the same or similarcomponents. The bone anchor system 100 can include a saddle 102, thebone fastener 14 and a uniplanar coupling system 106. It should be notedthat although not illustrated herein, the bone anchor system 100 caninclude the pressure cap 17, if desired.

With reference to FIGS. 12-15, the saddle 102 can be substantiallyU-shaped and symmetrical with respect to a longitudinal axis L definedby the bone anchor system 100 (FIG. 14). The saddle 102 can include theproximal end 20 and a second or distal end 110. The distal end 110 canbe generally rectangular, and can include the receiver surface 22 a anda bottom surface 110 b. It should be noted, however, that the distal end110 can have any desired shape, such as circular, octagonal, etc. Thedistal end 110 can also include a central aperture or central bore 112and at least one coupling apertures or coupling bore 114. The centralbore 112 can be defined through the distal end 22 from the receiversurface 22 a to the bottom surface 110 b. Generally, the central bore112 can be sized to receive the bone fastener 14, and can cooperate withthe coupling system 106 to allow the bone fastener 14 to move in onlyone plane. The central bore 112 can include the first sidewall 42, thesecond sidewall 44, a third sidewall 116 and the fourth sidewall 48.Generally, the first sidewall 42 can be opposite, but not identical tothe third sidewall 116.

In one example, the third sidewall 116 can include the limiting lip 50and a tapered portion 116 a. The tapered portion 116 a can be defined inthe third sidewall 116 adjacent to the bottom surface 110 b to providerelief for the uniplanar motion of the bone fastener 14. Thus, thetapered portion 116 a can cooperate with the coupling system 106 toenable the bone fastener 14 to move further in only one plane.Generally, the tapered portion 16 a can be sized to permit angularmotion of the bone fastener 14 in the single plane. For example, thetapered portion 116 a can have a slope of about negative 30 degrees toabout negative 60 degrees relative to the longitudinal axis L. The slopeof the tapered portion 116 a along with the lip 50 can define an angularlimit for the motion of the bone fastener 14 relative to the thirdsidewall 116 of the saddle 12.

With reference to FIG. 12, the at least one coupling bore 114 cancomprise a single coupling bore 114 defined through the first sidewall42. As the coupling bore 114 can be substantially similar to one of thecoupling bores 38 discussed with regard to FIGS. 1-11, the coupling bore114 need not be discussed in great detail herein. Briefly, however, thecoupling bore 114 can cooperate with the coupling system 106 to enablethe bone fastener 14 to move in only one plane.

With reference to FIGS. 12-15, the coupling system 106 can comprise atleast one pin 118, and in this example, the coupling system 106 caninclude a single pin 118. As the pin 118 can be substantially similar toone of the pins 54 discussed with regard to FIGS. 1-11, the pin 118 neednot be discussed in great detail herein. Briefly, however, the pin 118can include a bearing surface 118 a. The pin 118 can be received withinthe channel 52 such that the bearing surface 118 a can contact the firstbearing surface 56 a of the bone fastener 14 to enable the bone fastener14 to move in only one plane.

In order to assemble the bone anchor system 100, the pressure cap 17, ifemployed, can be positioned in the central bore 36 of the saddle 102such that the projections 64 a, 66 a are in contact with the lips 50.Then, the bone fastener 14 can be positioned through the central bore 36of the saddle 102. Next, the pin 118 of the coupling system 106 can beinserted or pressed through the coupling bore 114, into the channel 52of the first sidewall 42 of the saddle 102. Once the coupling system 106is pressed into the saddle 102, the bone fastener 14 can be retained inthe saddle 102 such that the bone fastener 14 is movable in only oneplane.

In this regard, with reference to FIGS. 13-15, the first planar surface56 c and second planar surface 56 d of the bone fastener 14 can be incontact with the smooth or planar second sidewall 44 and fourth sidewall48 of the central bore 36, thereby defining the motion of the bonefastener 14 as a single plane. The single plane of motion can be definedby the bearing surface 118 a of the pin 118, the non-tapered portion ofthe third sidewall 116 and the lips 50 of the first sidewall 42 andthird sidewall 116.

In one example, the bearing surface 118 a of the pin 118 can contact thefirst bearing surface 56 a (FIG. 13), while the non-tapered portion ofthe third sidewall 116 can contact the second bearing surface 56 b ofthe bone fastener 14 to enable the bone fastener 14 to articulaterelative to the coupling system 106 (FIG. 15).

As the surgical insertion and use of the bone anchor system 100 in afixation procedure can be similar to the surgical insertion andinsertion of the bone anchor system 10 in a fixation procedure, thesurgical insertion and use of the bone anchor system 100 need not bediscussed in great detail herein.

With reference now to FIGS. 16-24, in one example, a bone anchor system200 can be employed with the connecting rod 18 to repair a damagedportion of an anatomy. As the bone anchor system 200 can be similar tothe bone anchor system 10 described with reference to FIGS. 1-11, onlythe differences between the bone anchor system 10 and the bone anchorsystem 200 will be discussed in great detail herein, and the samereference numerals will be used to denote the same or similarcomponents. The bone anchor system 200 can include a saddle 202, a bonefastener 204 and a uniplanar coupling system 206. The bone anchor system200 can also include the pressure cap 17, if desired.

With reference to FIGS. 16-19, the saddle 202 can be substantiallyU-shaped and symmetrical with respect to a longitudinal axis L definedby the bone anchor system 200. The saddle 202 can include the proximalend 20 and a second or distal end 210. The distal end 210 can begenerally rectangular, and can include the receiver surface 22 a and abottom surface 210 b. The distal end 210 can also include a centralaperture or central bore 212 and at least one coupling aperture orcoupling bore 214.

In one example, the central bore 212 can be formed along thelongitudinal axis L from the receiver surface 22 a to the bottom surface210 b. Generally, the central bore 212 can be sized to receive the bonefastener 204, and can cooperate with the coupling system 206 to allowthe bone fastener 204 to move in only one plane. With reference to FIGS.19-23, the central bore 212 can include a first sidewall 216, a secondsidewall 218, a third sidewall 220 and a fourth sidewall 222. The firstsidewall 216 can be opposite and substantially identical to the thirdsidewall 220, while the second sidewall 218 can be opposite andsubstantially identical to the fourth sidewall 222.

With reference to FIG. 24, in one example, the first sidewall 216 andthird sidewall 220 can each include the lip 50, if desired, which can beused to couple the pressure cap 17 to the saddle 202. The first sidewall216 and third sidewall 220 can also include a counter bore 224 formedadjacent to the bottom surface 22 b. The counter bore 224 can be definedfrom the second sidewall 218 to the fourth sidewall 222. The counterbore 224 can provide a contact or stop for the movement of the bonefastener 204 relative to the saddle 202.

In one example, with reference to FIGS. 18-24, the coupling bore 214 canbe defined through the second sidewall 218 and the fourth sidewall 222.Thus, the coupling bore 214 can be formed transverse to the longitudinalaxis L of the bone anchor system 200. With reference to FIG. 23, thecoupling bore 214 can have an axis A, which can be substantiallyperpendicular to the longitudinal axis L. The coupling bore 214 can haveany shape configured to receive the coupling system 206, and forexample, the coupling bore 214 can be annular. It should be noted,however, the coupling bore 214 could have any desired shape, such asrectangular, square, etc. The coupling bore 214 can receive the couplingsystem 206 to couple the bone fastener 204 to the saddle 202 such thatthe bone fastener 204 is confined to only one plane of motion, as willbe discussed in further detail herein.

With reference to FIG. 18, the bone fastener 204 can include a proximalend or head 230 and the shaft 58. The head 230 can be configured toretain the bone fastener 204 within the saddle 202. In one example, thehead 230 can be annular, and can have a thickness T. The thickness T canbe sized so that the head 230 can be retained within the central bore212. Optionally, the head 230 can include the bore 55, which can beconfigured to enable the bone fastener 204 to be coupled to a respectivevertebral body V. The head 230 can define a first surface 230 a, asecond surface 230 b, a first planar surface 230 c, a second planarsurface 230 d and a bore 230 e.

The first surface 230 a can be generally opposite the second surface 230b. The first surface 230 a and the second surface 230 b can beconfigured to articulate with the bearing surfaces 216 a, 220 a of thefirst sidewall 216 and the third sidewall 220, respectively, when thebone fastener 204 is positioned within the saddle 202. In one example,the first surface 230 a and the second surface 230 b can be generallyarcuate, concave surfaces that can rotate relative to the first sidewall216 and third sidewall 220 (FIGS. 20-22). The first surface 230 a andthe second surface 230 b can cooperate with the second sidewall 218, andthe fourth sidewall 222 or the coupling system 206 to enable the bonefastener 204 to move in only one plane, as will be discussed in greaterdetail herein.

With reference to FIG. 23, the first planar surface 230 c can begenerally opposite the second planar surface 230 d. The first planarsurface 230 c and the second planar surface 230 d can be adjacent to andsubstantially in contact with the second sidewall 218 and the fourthsidewall 222 when the bone fastener 204 is positioned within the saddle202. The first planar surface 230 c and the second planar surface 230 dcan cooperate with the second sidewall 218 and the fourth sidewall 222to prevent the motion of the bone fastener 204 relative to the secondsidewall 218 and the fourth sidewall 222. Thus, the first planar surface230 c and the second planar surface 230 d and the second sidewall 218and the fourth sidewall 222 can define or limit the motion of the bonefastener 204 to a single plane.

The bore 230 e can be defined through the first planar surface 230 c andthe second planar surface 230 d of the bone fastener 204. The bore 230 ecan generally be configured to be in communication with at least aportion of the coupling system 206, and thus, the bore 230 e can haveany suitable shape, such as rectangular, square, triangular, etc. In oneexample, with reference to FIG. 23, the bore 230 e can be generallyannular, and can have an axis A2, which can be parallel to the axis A ofthe coupling bore 214. The bore 230 e can receive at least a portion ofthe coupling system 206 to couple the bone fastener 204 to the saddle202 such that the bone fastener 204 can move in only one plane.

In this regard, with reference to FIG. 18, the coupling system 206 cancomprise a pin 236, which can be received through the coupling bore 214of the saddle 202 and the bore 230 e of the bone fastener 204. The pin236 can be composed of any suitable biocompatible material, such as abiocompatible metal, metal alloy or polymer. The pin 236 can couple thebone fastener 204 to the saddle 202, while defining a pivot axis for themovement of the bone fastener 204, as shown in FIGS. 20-22. In thisregard, the bone fastener 204 can rotate about the pin 236 or the bonefastener 204 and pin 236 can rotate about the axis A in only one planeperpendicular to the axis A.

In order to assemble the bone anchor system 200, the pressure cap 17, ifemployed, can be positioned in the central bore 212 of the saddle 202such that the projections 64 a, 66 a are in contact with the first lips50 (FIG. 24). Then, the bone fastener 204 can be positioned through thecentral bore 212 of the saddle 202. Next, the pin 236 of the couplingsystem 206 can be inserted or pressed through the coupling bore 214 ofthe saddle 102 and the bore 230 e of the bone fastener 204. Once thecoupling system 206 is pressed into the saddle 102 through the bonefastener 204, the bone fastener 204 can be retained in the saddle 202such that the bone fastener 204 is movable in only one plane.

In this regard, with reference to FIG. 23, the first planar surface 56 cand second planar surface 56 d of the bone fastener 14 can be in contactwith the smooth or planar second sidewall 218 and fourth sidewall 222 ofthe central bore 212, thereby defining or limiting the motion of thebone fastener 204 to a single plane. As shown in FIGS. 20-22, the singleplane of motion can be defined by the pin 236. The pin 236 can enablethe bone fastener 204 to move between the counter bore 224 of the firstsidewall 216 and third sidewall 220.

In other words, during the movement of the bone fastener 204, the firstsurface 230 a and the second surface 230 b can contact the firstsidewall 216 and third sidewall 220, and the bone fastener 204 canarticulate relative to the first sidewall 216 and third sidewall 220about the pin 236 (FIGS. 20 and 22). The counter bore 224 of the centralbore 212 can limit the articulation of the bone fastener 204 relative tothe coupling system 206. Thus, the saddle 202 and the coupling system206 can define or limit the motion of the bone fastener 204 to a singleplane.

As the surgical insertion and use of the bone anchor system 200 in afixation procedure can be similar to the surgical insertion andinsertion of the bone anchor system 10 in a fixation procedure, thesurgical insertion and use of the bone anchor system 200 need not bediscussed in great detail herein.

With reference now to FIGS. 25-30, in one example, a bone anchor system300 can be employed with the connecting rod 18 to repair a damagedportion of an anatomy. As the bone anchor system 300 can be similar tothe bone anchor system 10 described with reference to FIGS. 25-30, onlythe differences between the bone anchor system 10 and the bone anchorsystem 300 will be discussed in great detail herein, and the samereference numerals will be used to denote the same or similarcomponents. The bone anchor system 300 can include a saddle 302, a bonefastener 304 and a uniplanar coupling system 306.

With reference to FIGS. 25-27, the saddle 302 can be substantiallyU-shaped and symmetrical with respect to a longitudinal axis L definedby the bone anchor system 300. The saddle 302 can include the proximalend 20 and a second or distal end 310. The distal end 310 can begenerally conical and can include a slight taper. It should be noted,however, that the distal end 310 can have any desired shape, such asrectangular, circular, octagonal, etc. The distal end 310 can includethe receiver surface 22 a and a bottom surface 310 b. The distal end 310can also include a central aperture or central bore 312, which canextend from the receiver surface 22 a to the bottom surface 310 b. Thecentral bore 312 can be spherical and sized to receive the bone fastener304, and can cooperate with the coupling system 306 to allow the bonefastener 304 to move in only one plane.

With reference to FIGS. 27 and 30, the central bore 312 can include afirst sidewall 316, a second sidewall 318, a third sidewall 320 and afourth sidewall 322. The first sidewall 316 can be opposite the thirdsidewall 320, while the second sidewall 318 can be opposite the fourthsidewall 322. In one example, the first sidewall 316, the secondsidewall 318, the third sidewall 320 and the fourth sidewall 322 can besubstantially identical. With reference to FIG. 30, each of the firstsidewall 316, the second sidewall 318, the third sidewall 320 and thefourth sidewall 322 can include a planar portion 324, a slot 326, anarcuate portion 328 and a tapered portion 330. Generally, the arcuateportion 328 can comprise a continuous sphere.

The planar portion 324 can be formed adjacent to the receiver surface 22a. Each of the planar portions 324 of the first sidewall 316, the secondsidewall 318, the third sidewall 320 and the fourth sidewall 322 cancooperate to form a substantially rectangular portion. In addition, theplanar portion 324 can cooperate with a portion of the coupling system306 to limit the motion of the bone fastener 304 to only one plane, aswill be discussed.

The slot 326 can be defined in the planar portion 324 of each of thefirst sidewall 316, the second sidewall 318, the third sidewall 320 andthe fourth sidewall 322. In one example, the slot 326 can be formedadjacent to the arcuate portion 328. It should be noted, however, thatthe slot 326 can be formed in the arcuate portion 328, if desired. Theslot 326 can be sized to receive a portion of the coupling system 306,and can couple a portion of the coupling system 306 to the saddle 302,as will be discussed.

The arcuate portion 328 can have a radius of curvature, which can extendfrom the slot 326 to the tapered portion 330. The arcuate portion 328can generally comprise a concave surface formed in each of the firstsidewall 316, the second sidewall 318, the third sidewall 320 and thefourth sidewall 322. Thus, the arcuate portion 328 can form asubstantially spherical portion of the central bore 312. The arcuateportion 328 can receive a portion of the coupling system 306, and cancooperate with the coupling system 306 to define or limit the motion ofthe bone fastener 304 to a single plane.

The tapered portion 330 can be formed adjacent to the distal end 22 ofthe saddle 302. The tapered portion 330 can define an area of reducedthickness in the distal end 310 of the saddle 302, which can provideclearance to enable the bone fastener 304 to move in the single planerelative to the saddle 302.

With reference to FIG. 26, the bone fastener 304 can include a proximalend or head 340 and the shaft 58. In one example, the head 340 caninclude a projection 342, the bore 55 and a groove 344. The projection342 can be a hemispherical ring, and can extend from a surface S of thehead 340. The projection 342 can have a width Wp, which can be selectedto enable the bone fastener 304 to be coupled to a portion of thecoupling system 306. As will be discussed, the projection 342 can definea bearing surface 342 a, which can enable the bone fastener 304 to moverelative to the saddle 302 via the receiver surface 356. Two planarsurfaces 342 b can be formed on opposite sides and can be generallyperpendicular to the bearing surface 342 a, to cooperate with thecoupling system 306 to prevent the motion of the bone fastener 304 inmore than one plane. The projection 342 can also define a peak or apex,through which the bore 55 can be defined.

The groove 344 can be defined below the surface S of the head 340, andcan extend about a circumference of the head 340. The groove 344 can beconfigured to receive a portion of the coupling system 306 to couple thecoupling system 306 to the bone fastener 304. It should be noted,however, that any suitable mechanism could be employed to couple theportion of the coupling system 306 to the bone fastener 304, such asmechanical fasteners, snap-fit, adhesives, etc.

With continued reference to FIG. 26, the coupling system 306 cancomprise a cap 350, a support ring 352 and at least one support 354. Thecap 350 can be substantially symmetrical about the longitudinal axis L.The cap 350 can be shaped and sized to be positioned within therectangular portion of the central bore 312 defined by the planarportions 324, as shown in FIG. 30. The cap 350 can be composed of anysuitable biocompatible material, such as a biocompatible metal, metalalloy and/or polymer. With reference to FIGS. 26 and 28, the cap 350 caninclude a top or receiver surface 356, a bottom surface 358, centralbore or aperture 360 and a groove 362.

The receiver surface 356 of the cap 350 can receive a portion of theconnecting rod 18, and can be substantially similar in shape to thereceiver surface 22 a of the saddle 302. With reference to FIG. 28A, thebottom surface 358 can be opposite the receiver surface 356, and caninclude at least one protrusion 364. In one example, the bottom surface358 can include two protrusions 364, which can be spaced apart by adistance D. The distance D can be substantially equal to the width Wp ofthe projection 342 of the head 340 of the bone fastener 304 so that theprojection 342 can be received between the two protrusions 364. Theportion of the bottom surface 358 between the two protrusions 364 cancomprise a bearing surface 358 a, which can mate with the bearingsurface 342 a of the head 340 to enable the bone fastener 304 toarticulate relative to the coupling system 306.

Each of the protrusions 364 can be triangular in shape, and can includeat least one edge 364 a and an interior planar surface 364 b. In thecase of a triangular shaped protrusion 364, each protrusion 364 caninclude two edges 364 a. Each of the edges 364 a can serve as a stop orlimit for the motion of the bone fastener 304 in the single plane. Inthis regard, each of the edges 364 a can contact a portion of the atleast one support 354, thereby limiting further movement of the bonefastener 304. The interior planar surfaces 364 b of the protrusions 364can be adjacent to the planar surfaces 342 b of the head 340 of the bonefastener 304 to limit the motion of the bone fastener 304 to a singleplane. In other words, the contact between the interior planar surfaces364 b of the cap 350 and the planar surfaces 342 b of the head 340 canprevent the movement of the bone fastener 304 in the direction of eitherinterior planar surface 364 b. Thus, the cap 350 can limit the motion ofthe bone fastener 304 to only one plane, as will be discussed furtherherein.

The aperture 360 can be defined through the receiver surface 356 and thebottom surface 358. The aperture 360 can enable a suitable tool to passthrough the cap 350 and engage the bore 55 to couple the bone fastener304 to the anatomy. The groove 362 can extend outwardly from the cap350, and can be formed about an outer surface 350 a of the cap 350. Thegroove 362 can be sized to cooperate with the slot 326 of the saddle 302to couple the cap 350 to the saddle 302 (FIG. 30). In one example, thegroove 362 can be configured such that support ring 352 can snap intoengagement with the slot 326. It should be noted, however, that anysuitable coupling technique could be used to secure the cap 350 to thesaddle 302, such as a flange, press fit, etc.

With reference back to FIG. 26, the coupling system 306 can include thesupport ring 352. The supporting ring 352 can be configured to bereceived within the groove 344 of the head 340 (FIG. 30). In oneexample, the supporting ring 352 can be snap-fit into the groove 344 andgroove 362, however, the support ring 352 can be coupled to the groove344 and groove 362 in any desired manner. Further, the support ring 352could be integrally formed with the at least one support 354, ifdesired. The support ring 352 can couple the at least one support 354 tothe bone fastener 304.

The at least one support 354 can retain the bone fastener 304 within thesaddle 302. In one example, the at least one support 354 can comprisetwo supports 354, which together can surround the circumference of thehead 340 of the bone fastener 304 (FIG. 30). It should be noted,however, that more or less supports 354 (e.g. one) could be employed toretain the head 340 of the bone fastener 304 within the saddle 302, ifdesired. The supports 354 can be received within the spherical portionof the central bore 312 defined by the arcuate portions 328 when thebone anchor system 300 is assembled (FIG. 30). With reference to FIG.29, the supports 354 can each include a first end 370, a second end 372,a first or proximal side 374, a second or distal side 376, an interiorsurface 378 and an exterior surface 380.

The first end 370 and second end 372 can each be angled or slopedrelative to the longitudinal axis L of the bone anchor system 300. Thesloped nature of the first end 370 and second end 372 can facilitate theplacement of the supports 354 relative to each other. The proximal side374 can be adjacent to the head 340 of the bone fastener 304, while thedistal side 376 can be adjacent to the shaft 58 of the bone fastener304. The proximal side 374 can have a larger radius of curvature thanthe radius of curvature of the distal side 376 as the supports 354 canbe configured to mate with the head 340 and shaft 58 of the bonefastener 304. The proximal side 374 can include a notch 374 a, which canallow a suitable instrument to engage the support 354 for coupling anduncoupling the support 354 from the bone fastener 304.

The interior surface 378 can include a channel 378 a and a collar 378 b.The channel 378 a can be formed adjacent to the proximal side 374. Thechannel 378 a can extend for a substantial majority of the interiorsurface 378 and can be sized to mate with the support ring 352 to couplethe support 354 to the bone fastener 304. The collar 378 b can be formedadjacent the distal side 376, and can also extend for a substantialmajority of the interior surface 378. The collar 378 b can be configuredto mate with a portion of the shaft 58 of the bone fastener 304 when thesupport 354 is coupled to the support ring 352. The exterior surface 380of the support 354 can be generally smooth to contact the sphericalportion of the central bore 312.

With reference to FIGS. 26 and 30, in order to assemble the bone anchorsystem 300, the support ring 352 can be coupled to the groove 344 of thebone fastener 304. Then, the bone fastener 304 can be coupled to thesaddle 302. In this regard, the bone fastener 304 can be advanced intothe central bore 312 from the distal end 310 of the saddle 302 until theprojection 342 of the bone fastener 304 is positioned between theprotrusions 364 of the cap 350. Next, the supports 354 can be coupled tothe bone fastener 304 via the engagement of the channel 378 a with thesupport ring 352. The cap 350 can be positioned within the central bore312 of the saddle 302, such that the cap 350 is in contact with therectangular portion of the central bore 312 (FIG. 30). Once the cap 350is coupled to the saddle 302, the movement of the bone fastener 304 isdefined or limited to one plane, as shown in FIG. 30.

In this regard, the planar surfaces 342 b of the head 340 can cooperatewith the interior planar surfaces 364 b of the cap 350 to limit themotion of the bone fastener 304 in the direction of either interiorplanar surface 364 b. Thus, the cap 350 and head 340 of the bonefastener 304 limit the bone fastener 304 to a single plane of motion.The bearing surface 342 a of the head 340 can allow the head 340 toarticulate on the bearing surface 358 a of the cap 350. The relativemovement between the bearing surface 342 a of the bone fastener 304 andthe bearing surface 358 a of the cap 350 can be defined by the edges 364a, which can contact a respective one of the supports 354 to preventadditional angular movement of the bone fastener 304 in the singleplane. Thus, the saddle 302 and the coupling system 306 can define orlimit the motion of the bone fastener 304 to a single plane.

As the surgical insertion and use of the bone anchor system 300 in afixation procedure can be similar to the surgical insertion andinsertion of the bone anchor system 10 in a fixation procedure, thesurgical insertion and use of the bone anchor system 300 need not bediscussed in great detail herein.

With reference now to FIGS. 31-35, in one example, a bone anchor system400 can be employed with the connecting rod 18 to repair a damagedportion of an anatomy. As the bone anchor system 400 can be similar tothe bone anchor system 300 described with reference to FIGS. 25-30, onlythe differences between the bone anchor system 300 and the bone anchorsystem 400 will be discussed in great detail herein, and the samereference numerals will be used to denote the same or similarcomponents. The bone anchor system 400 can include the saddle 302, abone fastener 404 and a uniplanar coupling system 406.

With reference to FIG. 32, the bone fastener 404 can include a proximalend or head 410 and the shaft 58. In one example, the head 410 caninclude a slot 412, at least one bearing surface 414, the bore 55 andthe groove 344. The slot 412 can be defined through the head 410 from afirst end 410 a to a second end 410 b. The slot 412 can include twoparallel planar sidewalls 412 a, which can be spaced apart by a distanceD4. The slot 412 can receive a portion of the coupling system 406, andthe sidewalls 412 a can cooperate with the coupling system 406 torestrict or limit the motion of the bone fastener 404 to a single plane,as will be discussed herein. The at least one bearing surface 414, inthis example, can comprise two bearing surfaces 414. The bearingsurfaces 414 can each comprise hemispherical portions of the head 410defined by the slot 412. The slot 412 can cooperate with the couplingsystem 406 to enable the bone fastener 404 to move in a single plane.

With reference to FIG. 31, the coupling system 406 can comprise a cap420, the support ring 352 and the at least one support 354. The cap 420can be substantially symmetrical about the longitudinal axis L. The cap420 can be shaped and sized to be positioned within the rectangularportion of the central bore 312 of the saddle 302. The cap 420 can becomposed of any suitable biocompatible material, such as a biocompatiblemetal, metal alloy and/or polymer. With reference to FIGS. 33 and 34,the cap 420 can include the top or receiver surface 356, a bottomsurface 422, the aperture 360 and the groove 362.

The bottom surface 422 can be opposite the receiver surface 356, and caninclude at least one protrusion 424 and at least one bearing surface426. In one example, the protrusion 424 can be triangular in shape, andcan extend outwardly from the bottom surface 422. The protrusion 424 canbe sized to be received within the slot 412 of the head 410, and thus,can have a width W4, which can be substantially equal to a width Ws ofthe slot 412. The protrusion 424 can include at least one edge 424 a andan interior planar surface 424 b.

In this example, the protrusion 424 can include two edges 424 a. Each ofthe edges 424 a can define the motion of the bone fastener 404 in thesingle plane. In this regard, each of the edges 424 a can contact aportion of the slot 412, thereby limiting further movement of the bonefastener 404. The interior planar surfaces 424 b of the protrusions 424can be adjacent to the planar sidewalls 412 a of the slot 412 of thebone fastener 404 to limit the motion of the bone fastener 404 to asingle plane. In other words, the contact between the interior planarsurfaces 424 b of the cap 420 and the planar sidewalls 412 a of the head410 can prevent the movement of the bone fastener 404 in the directionof either planar sidewall 412 a. Thus, the cap 420 can cooperate withthe head 410 to define or limit the motion of the bone fastener 404 toonly one plane, as shown in FIG. 35.

With reference now to FIG. 34, the at least one bearing surface 426 ofthe bottom surface 422, in this example, can comprise two bearingsurfaces 426, which can be defined adjacent to each interior planarsurface 424 b. It should be noted, however, that the bottom surface 422can include no bearing surfaces 426, if desired. The bearing surfaces426 can cooperate with the bearing surfaces 414 of the head 410 toenable the bone fastener 404 to move or articulate relative to thesaddle 302 in only one plane. In this example, the single plane ofmotion can be defined by the bearing surfaces 414 of the head 410 andthe edges 424 a of the cap 420. The relative movement between thebearing surfaces 414 of the bone fastener 404 and the bearing surfaces426 of the cap 420 can be limited by the edges 424 a, which can contacta portion of the slot 412 to prevent additional movement of the bonefastener 404 in the single plane, as illustrated in FIG. 35.

With reference to FIGS. 31-35, in order to assemble the bone anchorsystem 400, the support ring 352 can be coupled to the groove 344 of thebone fastener 404. Then, the bone fastener 404 can be coupled to thesaddle 302. In this regard, the bone fastener 404 can be advanced intothe central bore 312 from the distal end 310 of the saddle 302 until theprotrusion 424 of the cap 420 is received by the slot 412 of the bonefastener 404. Next, the supports 354 can be coupled to the bone fastener404 via the engagement of the channel 378 a with the support ring 352.The cap 420 can be positioned within the central bore 312 of the saddle302, such that the cap 420 is in contact with the rectangular portion ofthe central bore 312. Once the cap 420 is coupled to the saddle 302, themovement of the bone fastener 404 is restricted or limited to one plane,as discussed.

As the surgical insertion and use of the bone anchor system 400 in afixation procedure can be similar to the surgical insertion andinsertion of the bone anchor system 300 in a fixation procedure, thesurgical insertion and use of the bone anchor system 400 need not bediscussed in great detail herein.

With reference now to FIGS. 36-43, in one example, a bone anchor system500 can be employed with the connecting rod 18 to repair a damagedportion of an anatomy. As the bone anchor system 500 can be similar tothe bone anchor system 300 described with reference to FIGS. 25-30, onlythe differences between the bone anchor system 300 and the bone anchorsystem 500 will be discussed in great detail herein, and the samereference numerals will be used to denote the same or similarcomponents. The bone anchor system 500 can include a saddle 502, thebone fastener 304 and a uniplanar coupling system 506.

With reference to FIGS. 36-38, the saddle 502 can be substantiallyU-shaped and symmetrical with respect to a longitudinal axis L definedby the bone anchor system 500. The saddle 502 can include a first orproximal end 510 and the distal end 310. The proximal end 510 caninclude a first arm 512 and a second arm 514. The first arm 512 andsecond arm 514 can extend upwardly from the distal end 310 to define theU-shape. Each of the first arm 512 and the second arm 514 can includethe insertion feature 28, the mating portion 30, a notch 516 and alocking portion 518. The mating portion 30 can be formed on an interiorsurface 512 a, 514 a, of each of the first arm 512 and second arm 514,respectively.

The notch 516 can be defined on the interior surfaces 512 a, 514 a ofthe first arm 512 and the second arm 514. In one example, the notch 516can be formed between the mating portion 30 and the locking portion 518.The notch 516 can provide clearance for a portion of the coupling system506, as will be discussed in greater detail herein.

The locking portion 518 can be formed between the proximal end 510 andthe distal end 310. In one example, the locking portion 518 can bedefined about a circumference of the proximal end 510, adjacent to ornear the distal end 310. The locking portion 518 can include a pluralityof teeth 518 a, which can engage a portion of the coupling system 306 toprevent the rotation of a portion of the coupling system 306 relative tothe saddle 502.

With reference to FIGS. 37 and 39, the coupling system 406 can comprisea cap 530, a locking member 532, the support ring 352 and the supports354. The cap 530 can be substantially symmetrical about the longitudinalaxis L. The cap 530 can be shaped and sized to be positioned within therectangular portion of the central bore 312 defined by the planarportions 324 (FIG. 42). The cap 530 can be composed of any suitablebiocompatible material, such as a biocompatible metal, metal alloyand/or polymer. With reference to FIG. 39, the cap 530 can include a topsurface 533, the bottom surface 358, and the aperture 360.

The top surface 533 can be opposite the bottom surface 358. The topsurface 533 can include a projection 534 and a cap locking portion 536.The projection 534 can extend proximally from the cap 530. In oneexample, the projection 534 can be annular, however, the projection 534could have any desired shape, such as square, rectangular, triangular,etc. The projection 534 can define a receiver surface 534 a. Thereceiver surface 534 a can be substantially similar in shape to thereceiver surface 22 a of the saddle 502. The aperture 360 can be definedfrom the receiver surface 534 a to the bottom surface 358.

The cap locking portion 536 can be formed about a periphery of theprojection 534. The cap locking portion 536 can include a plurality ofteeth 536 a. The teeth 536 a can mate with a portion of the lockingmember 532 to prevent the rotation of the cap 530 relative to the saddle502.

With reference to FIG. 37, the locking member 532 can comprise a ring,which can include a plurality of interior teeth 532 a and a plurality ofexterior teeth 532 b. The interior teeth 532 a can mate with the teeth536 a of the cap locking portion 536 to couple the locking member 532 tothe cap 530. The interior teeth 532 a can generally be formed about aninner circumference of the locking member 532, while the exterior teeth532 b can be formed about an outer circumference of the locking member532. The exterior teeth 532 b can mate with the teeth 518 a of thelocking portion 518 of the saddle 502 to prevent the rotation of the cap530 relative to the saddle 502, when the locking member 532 is in asecond, locked position. As will be discussed, in a first, unlockedposition, the cap 530 can rotate relative to the saddle 502 to enable anoperator to select a single desired plane for the planar movement of thebone fastener 304.

It should be noted, however, that the locking member 532, cap lockingportion 536 and locking portion 518 of the saddle 502 can have anysuitable configuration in which the locking member 532 can be moved toprevent the rotation of the cap 530 relative to the saddle 502. In oneexample, with reference to FIG. 40, a locking member 532 c can comprisea ring having a rectangular interior planar surface 532 d and theexterior teeth 532 b. In this example, a cap 530 c can include arectangular projection 534 c and a rectangular planar cap lockingportion 536 c. The interior planar surface 532 d of the locking member532 c can mate with the rectangular planar cap locking portion 536 c ofthe cap 530 c to couple the cap 530 c to the locking member 532 c.

In a second example, with reference to FIG. 41, a locking member 532 ecan comprise a rectangular ring having the interior teeth 532 a and aplanar exterior surface 532 f. In this example, a locking portion of asaddle can comprise a rectangular planar surface, which can extend aboutan interior periphery of the saddle 502. The planar exterior surface 532f of the locking member 532 e can mate with the square planar lockingportion of the saddle to prevent the rotation of the cap 530 relative tothe saddle 502.

With reference back to FIGS. 37, 42 and 43, in order to assemble thebone anchor system 500, the support ring 352 can be coupled to thegroove 344 of the bone fastener 304. Then, the bone fastener 304 can becoupled to the saddle 502. Once the bone fastener 304 is coupled to thesaddle 502, the cap 530 can be rotated within the saddle 502 with asuitable instrument until a desired single plane is selected for therotation of the bone fastener 304. Next, the supports 354 can be coupledto the bone fastener 304 via the engagement of the channel 378 a withthe support ring 352. The cap 530 can be positioned within the centralbore 312 of the saddle 502, such that the cap 530 is in contact with theteeth 536 a of the cap locking portion 536. With the cap 530 positionedwithin the central bore 312, the locking member 532 can be insertedbetween the first arm 512 and second arm 514.

In the first, unlocked position (FIG. 42), the locking member 532 can beadjacent to the notches 516 of the first arm 512 and second arm 514. Thelocking member 532 can slide or rotate relative to the saddle 502 toallow the cap 530 to rotate relative to the saddle 502. An operator canmove the saddle 502 until the bone fastener 304 is aligned with thedesired single plane of motion. Then, the operator can move the lockingmember 532 into a second, locked position (FIG. 43) so that the interiorteeth 532 a engage the teeth 536 a of the cap locking portion 536, andthe exterior teeth 532 b engage the teeth 518 a of the locking portion518 of the saddle 502 to prevent the rotation of the cap 530 relative tothe saddle 502.

Thus, the bone anchor system 500 can enable an operator to select adesired single plane of motion for the saddle 502 relative to the bonefastener 304, which can enable the operator to customize the bone anchorsystem 500 for the particular patient. As the surgical insertion and useof the bone anchor system 500 in a fixation procedure can be similar tothe surgical insertion and insertion of the bone anchor system 300 in afixation procedure, the surgical insertion and use of the bone anchorsystem 500 need not be discussed in great detail herein.

With reference now to FIGS. 44-46, in one example, a bone anchor system600 can be employed with the connecting rod 18 to repair a damagedportion of an anatomy. As the bone anchor system 600 can be similar tothe bone anchor system 300 described with reference to FIGS. 25-30, onlythe differences between the bone anchor system 300 and the bone anchorsystem 600 will be discussed in great detail herein, and the samereference numerals will be used to denote the same or similarcomponents. The bone anchor system 600 can include a saddle 602, thebone fastener 304 and a uniplanar coupling system 606.

The saddle 602 can be substantially U-shaped and symmetrical withrespect to a longitudinal axis L defined by the bone anchor system 600.The saddle 602 can include a first or proximal end 610 and the distalend 310. The proximal end 610 can include a first arm 612 and a secondarm 614. The first arm 612 and second arm 614 can extend upwardly fromthe distal end 310 to define the U-shape. Each of the first arm 612 andthe second arm 614 can include the insertion feature 28, the matingportion 30 and a locking portion 618. The mating portion 30 can beformed on an interior surface 612 a, 614 a, of each of the first arm 612and second arm 614, respectively.

The locking portion 618 can be formed between the proximal end 610 andthe distal end 310. In one example, the locking portion 618 can bedefined about a circumference of the proximal end 610, adjacent to thedistal end 310. The locking portion 618 can include a threaded portion618 a and a planar portion 618 b. Each of the threaded portion 618 a andthe planar portion 618 b can mate with a portion of the coupling system606 to prevent the rotation of a portion of the coupling system 606relative to the saddle 602.

The coupling system 606 can comprise a cap 630, a locking member 632, afastener 633, the support ring 352 and the supports 354. The cap 630 canbe substantially symmetrical about the longitudinal axis L, and can bereceived within the rectangular portion of the central bore 312. The cap630 can be composed of any suitable biocompatible material, such as abiocompatible metal, metal alloy and/or polymer. With reference to FIG.45, the cap 630 can include a top surface 634, the bottom surface 358and the aperture 360.

The top surface 634 can be opposite the bottom surface 358. The topsurface 634 can include a plurality of grooves or serrations 634 a. Theserrations 634 a can extend radially from the aperture 360, and can beformed about a circumference of the top surface 634. The serrations 634a can mate with a portion of the locking member 632 to prevent therotation of the cap 630 relative to the saddle 602.

In this regard, with reference to FIG. 46, the locking member 632 cancomprise a rectangular plate, which can be received between the firstarm 612 and second arm 614 of the saddle 602. The locking member 632 caninclude a first or top surface 636, a second or bottom surface 638, aperiphery 640 and a bore 642, which can extend from the top surface 636to the bottom surface 638.

The top surface 636 can be generally smooth, and can be opposite thebottom surface 638. The bottom surface 638 can include a plurality ofgrooves or serrations 638 a. The serrations 638 a can extend radiallyfrom the bore 642, and can be formed about a circumference of the bottomsurface 636. The serrations 638 a can mate with the serrations 634 a ofthe cap 630. The periphery 640 can be substantially planar, and can besized to be positioned adjacent to the planar portion 618 b of thesaddle 602 to prevent the rotation of the cap 630 relative to the saddle602 when the locking member 632 is in a second, locked position. Thebore 642 can enable an instrument to pass through the coupling system606 to couple the bone fastener 304 to the anatomy.

With reference to FIG. 44, the fastener 633 can move the locking member632 from a first, unlocked position to the second, locked position. Itshould be understood, however, that the fastener 633 can be optional, asthe locking member 632 could be placed into engagement with the cap 630through any suitable technique. The fastener 633 can include a pluralityof threads 633 a. If employed, the fastener 633 be inserted between thefirst arm 612 and second arm 614 so that the threads 633 a can engagethe threaded portion 618 a of the saddle 602. The advancement of thefastener 633 within the saddle 602 can move or advance the lockingmember 632 from the first, unlocked position to the second, lockedposition. As will be discussed, in the first, unlocked position, the cap630 can rotate relative to the saddle 602 to enable an operator toselect a single desired plane for the planar movement of the bonefastener 304.

In order to assemble the bone anchor system 600, the support ring 352can be coupled to the groove 344 of the bone fastener 304. Then, thebone fastener 304 can be coupled to the saddle 602. Next, the supports354 can be coupled to the bone fastener 304. The cap 630 can bepositioned within the central bore 312 of the saddle 602, such that thecap 630 is in contact with the rectangular portion of the central bore312. With the cap 630 positioned within the central bore 312, thelocking member 632 can be inserted between the first arm 612 and secondarm 614 such that the locking member 632 is adjacent to the threadedportion 618 a of the saddle 602.

With the locking member 632 in the first, unlocked position, the lockingmember 632 can be positioned adjacent to the threaded portion 618 a ofthe first arm 512 and second arm 514. An operator can move the saddle602 until the saddle 602 is aligned with the desired single plane ofmotion. Then, the operator can insert the fastener 633 into the saddle602. Using a suitable instrument, the fastener 633 can be advanced toengage the threads 633 a of the fastener 633 with the threaded portion618 b of the saddle 602. The engagement of the fastener 633 with thethreaded portion 618 b can move the locking member 632 from the first,unlocked position to the second, locked position. In the second, lockedposition, the serrations 638 a of the locking member 632 can bemeshingly engaged with the serrations 634 a of the cap 630 to preventthe rotation of the cap 630 relative to the saddle 602.

Thus, the bone anchor system 600 can enable an operator to select adesired single plane of motion for the saddle 602 relative to the bonefastener 304, which can enable the operator to customize the bone anchorsystem 600 for the particular patient. As the surgical insertion and useof the bone anchor system 600 in a fixation procedure can be similar tothe surgical insertion and insertion of the bone anchor system 300 in afixation procedure, the surgical insertion and use of the bone anchorsystem 600 need not be discussed in great detail herein.

With reference now to FIG. 47, while the bone anchor system 10 has beendescribed herein as having an optional pressure cap 17 that has a smoothconcave bottom surface 62, those of skill in the art will appreciatethat the present disclosure, in its broadest aspects, may be constructedsomewhat differently. In this regard, the pressure cap 17 could includea plurality of teeth 17 a and/or a plurality of teeth 17 b. The teeth 17a can bite into the first bearing surface 56 a and the second bearingsurface 56 b of the head 56 of the bone fastener 14 to further controlthe rotation of the bone fastener 14 relative to the saddle 12. Theplurality of teeth 17 b can provide an additional locking or frictionalforce for coupling the connecting rod 18 to the bone anchor system 10.

As a further example, with reference to FIG. 48, the first bearingsurface 56 a and the second bearing surface 56 b of the head 56 of thebone fastener 14 could each include a plurality of teeth 700. Theplurality of teeth 700 can bite into the smooth bottom surface 62 of thepressure cap 17 or can engage the teeth 17 a of the pressure cap 17 tofurther control the rotation of the bone fastener 14. If the pressurecap 17 is not employed, then the teeth 700 of the bone fastener 14 canbite into the connecting rod 18 to provide an additional coupling forceto the connecting rod 18.

With reference now to FIGS. 49-54, in one example, a bone anchor system800 can be employed with the connecting rod 18 to repair a damagedportion of an anatomy. As the bone anchor system 800 can be similar tothe bone anchor system 10 described with reference to FIGS. 1-11, onlythe differences between the bone anchor system 10 and the bone anchorsystem 800 will be discussed in great detail herein, and the samereference numerals will be used to denote the same or similarcomponents. The bone anchor system 800 can include a saddle 802, a bonefastener 804 and the uniplanar coupling system 16. The uniplanarcoupling system 16 can enable the saddle 802 to move relative to thebone fastener 804 in only a single plane. The bone anchor system 800 canalso include a pressure cap 806, which can be retained within the saddle802 via a retaining ring 808 (FIG. 50).

As will be discussed herein, the saddle 802 can be configured to receivethe connecting rod 18, which can be used to interconnect multiple boneanchor systems 800 (the same or different types) in an exemplary spinalfixation procedure. It should be noted, however, that although the boneanchor system 800 is generally illustrated and described herein a singleassembly for use with a single connecting rod 18, any combination ofbone anchor systems 800 and connecting rods 18 can be employed during asurgical procedure.

For example, in a single level spinal fixation procedure, two boneanchor systems 800 can receive a single connecting rod 18. A multiplelevel spinal fixation procedure, however, will generally requireadditional bone anchor systems 800, which can include other types ofbone anchor systems, such as those employing non-movable bone fasteners.In addition, the bone anchor systems 800 need not be coupled to adjacentvertebral bodies V, but rather, the bone anchor systems 800 can bepositioned so as to skip adjacent vertebral bodies V, if desired.

With reference to FIGS. 49-50, the saddle 802 can be substantiallyU-shaped and symmetrical with respect to a longitudinal axis L definedby the bone anchor system 800. The saddle 802 can include the first orproximal end 20 and a second or distal end 810. The proximal end 20 canbe integrally formed with the distal end 810 out of a suitablebiocompatible material, however, the proximal end 20 and distal end 810can be formed and coupled together through any suitable processingtechnique, such as machining and welding, etc.

With reference to FIGS. 50-54, the distal end 810 can be generallyrectangular, and can include the first, top or receiver surface 22 a andthe second or bottom surface 22 b. It should be noted, however, that thedistal end 810 can have any desired shape such as circular, octagonal,etc. In addition, the distal end 810 can include a central aperture orcentral bore 812 and the at least one or more coupling apertures orcoupling bores 38 (FIG. 50).

With reference to FIGS. 51-54, the central bore 812 can be definedthrough the distal end 22 from the receiver surface 22 a to the bottomsurface 22 b. Generally, the central bore 812 can be sized to receivethe bone fastener 804, and can cooperate with the coupling system 16 toallow the bone fastener 804 to move in only one plane. With reference toFIGS. 51-54, the central bore 812 can include a first or upper portion814 and a second or lower portion 816. The upper portion 814 can be incommunication with the lower portion 816 to enable receipt of the bonefastener 804, the coupling system 16 and the optional pressure cap 806within the saddle 802.

In this regard, the upper portion 814 of the central bore 812 can beconfigured to mate with the pressure cap 806. In one example, the upperportion 814 can be annular or cylindrical in shape to mate with anannular or cylindrical pressure cap 806. It should be noted, however,that the upper portion 814 can have any suitable shape that enablesreceipt of the pressure cap 806 within the central bore 812, such asrectangular, square, etc. In one example, with reference to FIG. 51, theupper portion 814 can include a first annular groove 818 and a secondannular groove 820. The first annular groove 818 can be adjacent to thereceiving portion 22 a of the saddle 802, and can have a diameter D8.The diameter D8 can be smaller than a diameter D9 of the second annulargroove 820. In this example, the first annular groove 818 can cooperatewith the retaining ring 808 to couple the pressure cap 806 to the saddle802, as will be discussed further herein.

The second annular groove 820 can be formed between the first annulargroove 818 and the lower portion 816. The second annular groove 820 canbe sized to receive the retaining ring 808. In this regard, due to thesmaller diameter D8 of the first annular groove 818, the retaining ring808 can remain seated within the second annular groove 820 therebyretaining the pressure cap 806 within the saddle 802. The second annulargroove 820 can also allow the bone fastener 804 to move relative to thesaddle 802 in the single plane, as will be discussed further herein.

With reference to FIGS. 51-54, the lower portion 816 can be between thesecond annular groove 820 and the bottom surface 22 b. The lower portion816 can include a first sidewall 822 (FIGS. 52-54), the second sidewall44 (FIG. 51), a third sidewall 824 (FIGS. 52-54) and the fourth sidewall48 (FIG. 51). Generally, the first sidewall 822 can be opposite andsubstantially identical to the third sidewall 824, while the secondsidewall 44 can be opposite and substantially identical to the fourthsidewall 48.

In one example, with reference to FIGS. 52-54, the first sidewall 822and the third sidewall 824 can each include a limiting projection or lip826 and the channel 52. The lip 826 can be formed or defined by aportion of the second annular groove 820. The lip 826 can control orlimit the range of uniplanar motion of the bone fastener 804, as will bediscussed herein.

As discussed previously herein, the channel 52 can be formed adjacent toor near the bottom surface 22 b. Each channel 52 can be in communicationwith a respective one of the coupling bores 38, and can define apassageway for receipt of a portion of the coupling system 16.Generally, the channel 52 can be circumferentially open to enable thecoupling system 16 to contact a portion of the bone fastener 804 toenable the bone fastener 804 to move in only one plane.

The bone fastener 804 can be received through the central bore 812 ofthe saddle 802, and can be coupled to the saddle 802 via the couplingsystem 16. With reference to FIG. 50, the bone fastener 804 can includea proximal end or head 830 and the distal end or shaft 58. The head 830can be configured to retain the bone fastener 804 within the saddle 802and to enable the bone fastener 804 to contact the pressure cap 806.

In one example, the head 830 can be generally arcuate, and can have athickness T. The thickness T can be sized to ensure that the head 830can move in a single plane. Optionally, the head 830 can also include abore 832, which can be configured to enable the bone fastener 804 to becoupled to a respective vertebral body V. In one example, the bore 832can have a hexagonal shape to matingly engage a suitable driving tool.If employed, the bore 832 can cooperate with the tool to align the shaft58 axially during the insertion of the bone fastener 804 into theanatomy.

The head 830 can define the first bearing surface 56 a, the secondbearing surface 56 b, the first planar surface 56 c, the second planarsurface 56 d, a first engagement or stepped surface 830 e and a secondengagement or stepped surface 830 f. The first bearing surface 56 a andthe second bearing surface 56 b can be adjacent to the first sidewall822 and the third sidewall 824 when the bone fastener 804 is positionedwithin the saddle 802. Similarly, the first planar surface 56 c and thesecond planar surface 56 d can be adjacent to the second sidewall 44 andthe fourth sidewall 48 when the bone fastener 804 is positioned withinthe saddle 802. The first bearing surface 56 a and the second bearingsurface 56 b can be in communication with a portion of the couplingsystem 16 so that the bone fastener 804 can articulate relative to thesaddle 802 in one plane. The first planar surface 56 c and the secondplanar surface 56 d can cooperate with the second sidewall 44 and thefourth sidewall 48 to restrict or prevent the motion of the bonefastener 14 in more than one plane.

The first stepped surface 830 e can be formed adjacent to the firstbearing surface 56 a, while the second stepped surface 830 f can beformed adjacent to the second bearing surface 56 b. The first steppedsurface 830 e and the second stepped surface 830 f can be coupled to orin contact with the pressure cap 806 when the bone anchor system 800 isassembled, as shown in FIGS. 52-54. The first stepped surface 830 e andthe second stepped surface 830 f can include one or more steps S, whichcan cooperate with a portion of the pressure cap 806 to assist infixedly locking the bone fastener 304 relative to the saddle 802. In oneexample, each of the first stepped surface 830 e and the second steppedsurface 830 f can include about eight steps S, however, any desirednumber of steps could be employed. Further, the steps S could beoptional, as the pressure cap 806 could engage a portion of the head 830that extends above the first bearing surface 56 a and the second bearingsurface 56 b.

With reference to FIGS. 50-54, the pressure cap 806 can be optionallycoupled to the head 830 of the bone fastener 804 to further distributeforces across the head 830 of the bone fastener 804. It should be notedthat the pressure cap 806 is optional, as the contact between the bonefastener 804 and the connecting rod 18 alone can distribute forcesacross the head 830 of the bone fastener 804. The pressure cap 806 cangenerally be sized to be positioned within the upper portion 814 of thecentral bore 812 of the saddle 802.

In one example, the pressure cap 806 can be sized such that a first ortop surface 840 of the pressure cap 806 extends slightly above thereceiver surfaces 22 a of the saddle 802 when the pressure cap 806 iscoupled to the saddle 802 (FIG. 49). This can allow the pressure cap 806to apply a force to the head 830 of the bone fastener 804 when theconnecting rod 18 is coupled to the saddle 802 via the set screw 32. Inaddition, the use of the pressure cap 806 with the bone fastener 804 canprovide a larger surface area for the distribution of forces acting onthe bone fastener 804. With reference to FIG. 50, the pressure cap 806can include the top surface 840 opposite a second or bottom surface 842,an annular or cylindrical sidewall 844, a groove 846 and an aperture orbore 848 defined from the top surface 840 to the bottom surface 842.

The top surface 840 can be generally smooth, and can be in contact witha portion of the connecting rod 18 when the connecting rod 18 is coupledto the saddle 802. Optionally, the top surface can also include achamfer 840 a disposed about the bore 848, which can aid in directing atool into and through the bore 848. The bottom surface 842 can be incontact with the head 830 of the bone fastener 804 when the bone anchorsystem 800 is assembled. The bottom surface 842 can include an optionalengagement surface or plurality of teeth 842 a, which can engage thefirst stepped surface 830 e and second stepped surface 830 f of the bonefastener 804 to assist in locking the bone fastener 804 relative to thesaddle 802. The plurality of teeth 842 a, if employed, can be definedabout a perimeter of the pressure cap 806. With reference to FIGS.52-54, a countersink 842 b can also be defined at the bottom surface842, adjacent to the teeth 842 a to enable the head 830 of the bonefastener 804 to move relative to the saddle 802. In this regard, thecountersink 842 b can provide clearance for the head 830 of the bonefastener 804 to move relative to the pressure cap 806 within the saddle802.

The cylindrical sidewall 844 of the pressure cap 806 can connect the topsurface 840 to the bottom surface 842 and can be sized to fit within theupper portion 814 of the saddle 802. The groove 846 can be formed alongthe sidewall 844, adjacent to the bottom surface 842. The groove 846 canreceive the retaining ring 808 to couple the pressure cap 806 to thesaddle 802.

Generally, the bore 848 can be defined about a central axis of thepressure cap 806. The bore 848 can be defined from the top surface 840to the bottom surface 842 to enable a tool to pass through the pressurecap 806 to couple the bone fastener 804 to the anatomy. The bore 848 canhave a diameter, which in one example, can be about as large as orlarger than a diameter of the bore 832 formed in the head 830 of thebone fastener 804, as shown in FIGS. 50-54.

With reference to FIG. 50, the retaining ring 808 can be used to couplethe pressure cap 806 to the saddle 802. In this regard, as discussed,the retaining ring 808 can be received within the groove 846 of thepressure cap 806 and a portion of the second annular groove 820 toretain the pressure cap 806 within the upper portion 814 of the centralbore 812 of the saddle 802. The retaining ring 808 can comprise anysuitable circular or semi-circular structure that can be received withinthe groove 846 of the pressure cap 808 and the second annular groove 820of the central bore 812. It should be noted that although the retainingring 808 is illustrated herein as being semi-circular or as having anopen perimeter, the retaining ring 808 could be circular or have aclosed perimeter if desired. Further, devices and techniques other thanthe retaining ring 808 could be employed to couple the pressure cap 806to the saddle 802, such as a flange, projection, press-fit, snap-fit,etc. If employed, the retaining ring 808 can be composed of abiocompatible material, such as a biocompatible metal, metal alloy orpolymer.

With general reference to FIGS. 49-54, the pressure cap 806 cancooperate with the saddle 802 and the coupling system 16 to enable thebone fastener 804 to move in one plane relative to the saddle 802. Theability of the bone fastener 804 to move in one plane relative to thesaddle 802 can allow the saddle 802 to move in one plane when the bonefastener 804 is fixedly coupled to the anatomy. In turn, this can allowthe surgeon to position the saddle 802 in a desired position relative tothe bone fastener 804 prior to coupling the connecting rod 18 to thesaddle 802 with the set screw 32. As the surgeon tightens the set screw32 onto the connecting rod 18, the connecting rod 18 can be pushed ontothe head 830 of the pressure cap 806, which can secure or fix the bonefastener 804 in the desired position relative to the saddle 802. Byallowing the surgeon to select a desired position for the saddle 802relative to the bone fastener 804, the surgeon can more easily insertthe connecting rod 18 into one or more saddles 802. In addition, thepositioning of the one or more saddles 802 prior to the coupling of theconnecting rod 18 can allow for a better alignment of the patient'sspine.

With reference to FIGS. 51-54, in order to assemble the bone anchorsystem 800, the retaining ring 808 can be positioned about the pressurecap 806, and the pressure cap 806 can be positioned in the upper portion814 of the central bore 812 of the saddle 802 such that the retainingring 808 is received within the second annular groove 820 of the upperportion 814. Then, the bone fastener 804 can be positioned into thelower portion 816 of the central bore 812 of the saddle 802. Next, thepins 54 of the coupling system 16 can be inserted or pressed through thecoupling bores 38, into the channels 52 of the first sidewall 822 andthird sidewall 824 of the central bore 812. Once the coupling system 16is pressed into the saddle 802, the bone fastener 804 can be retained inthe saddle 802 such that the bone fastener 804 is movable in only oneplane.

In this regard, the first planar surface 56 c and second planar surface56 d of the bone fastener 14 can be in contact with the smooth or planarsecond sidewall 44 and fourth sidewall 48 of the central bore 812,thereby restricting or limiting the motion of the bone fastener 804 to asingle plane, as shown in FIGS. 52-54. The single plane of motion can bedefined by the bearing surfaces 54 a of the pins 54 and contact betweenthe first stepped surface 830 e or second stepped surface 830 f and theteeth 842 a of the pressure cap 806. In addition, at least one of thelips 826 of the first sidewall 822 and third sidewall 824 can define thebearing surface by contacting the head 830 of the bone fastener 804 ifthe pressure cap 806 and/or the first and second stepped surfaces 830 e,830 f are not employed.

In one example, the bearing surfaces 54 a of the pins 54 can contact thefirst bearing surface 56 a and the second bearing surface 56 b of thebone fastener 804 to enable the bone fastener 804 to articulate relativeto the coupling system 16. As the bone fastener 804 moves or articulatesin the single plane, a portion of the first stepped surface 830 e andthe second stepped surface 830 f of the bone fastener 804 can contactthe teeth 842 a of the pressure cap 806, thereby preventing furthermovement or articulation of the bone fastener 804 (FIGS. 52 and 54).

In this regard, the bone fastener 804 can require about three points ofcontact to allow the motion of the bone fastener 804 to be a singleplane. In one example, the head 830 of the bone fastener 804 can requireabout three points or lines of contact to form a substantially circularpath or single substantially circular plane about which the bonefastener 804 can rotate. For example, the head 830 can contact each ofthe pins 54 and one of the teeth 842 a; one of the pins 54 and two ormore of the teeth 842 a; one of the pins 54, one of the teeth 842 a andone of the second or fourth sidewalls 44, 48 of the central bore 812,etc.

As the surgical insertion and use of the bone anchor system 800 in afixation procedure can be similar to the surgical insertion andinsertion of the bone anchor system 10 in a fixation procedure, thesurgical insertion and use of the bone anchor system 800 need not bediscussed in great detail herein. Briefly, however, with the bonefastener 804 coupled to the saddle 802 via the coupling system 16,surgical access can be made through the skin adjacent to the vertebralbodies V of interest, as previously described with regard to FIG. 1.

Next, one or more bone anchor systems 800 can be coupled to a respectivevertebral body V via the bone fastener 804. Various techniques can beused to couple the bone anchor systems 10 to the anatomy, such as thosedescribed in commonly owned U.S. Patent Publication No. 2008/0077138,filed on Apr. 20, 2007, previously incorporated by reference herein. Inone example, if each bone fastener 804 includes the bore 832 defined inthe head 830, a suitable tool can be coupled to the bore 832 to alignand drive the bone fastener 804 into the anatomy in a conventionalmanner. Once one or more of the bone anchor systems 800 are coupled tothe anatomy, the one or more saddles 802 can be moved into a desiredposition relative to the bone fastener 804 by the surgeon. Then, theconnecting rod 18 can be inserted into the saddle 802 of each of thebone anchor systems 800. Generally, the connecting rod 18 can beinserted such that the connecting rod 18 rests on the top surface 840 ofthe pressure cap 806.

With the connecting rod 18 positioned in the one or more saddles 802 ofthe bone anchor systems 800, the set screw 32 can be coupled to eachmating portion 30 of each saddle 802. The coupling of the set screw 32can apply a force to the pressure cap 806 to move the top surface 840 ofthe pressure cap 806 substantially adjacent to the receiver surfaces 22a of the saddle 802, if employed. This movement of the pressure cap 806can apply a force to the head 830 of the bone fastener 804, which candistribute forces over the head 830 of the bone fastener 804 and canfurther lock the bone fastener 804 in the desired position relative tothe saddle 802. The coupling of the set screw 32 to the saddle 802 canalso couple the connecting rod 18 to the bone anchor system 800.

As discussed, since the surgeon is able to position the one or moresaddles 802 relative to the bone fasteners 804 prior to coupling theconnecting rod 18 to the respective bone anchor system 800, the surgeoncan more easily insert the connecting rod 18 into the saddles 802. Inaddition, the positioning of the saddles 802 prior to the coupling ofthe connecting rod 18 can allow for a better alignment of the patient'sspine.

Accordingly, the bone anchor system 10, 100, 200, 300, 400, 500, 600,800 can be used to repair damaged tissue in the anatomy, such as in thecase of a spinal fixation or fusion procedure. By allowing the saddle12, 202, 302, 502, 602, 802 to move relative to the bone fastener 14,204, 304, 804 in only one plane, the surgeon can align the saddles 12,202, 302, 502, 602, 802 to allow for easier insertion of the connectingrod 18. In addition, the ability to select the single plane of motionfor the bone fastener 304 can enable the bone anchor system 500, 600 tobe used with a variety of different anatomical structures.

While specific examples have been described in the specification andillustrated in the drawings, it will be understood by those of ordinaryskill in the art that various changes can be made and equivalents can besubstituted for elements thereof without departing from the scope of thepresent teachings. Furthermore, the mixing and matching of features,elements and/or functions between various examples is expresslycontemplated herein so that one of ordinary skill in the art wouldappreciate from the present teachings that features, elements and/orfunctions of one example can be incorporated into another example asappropriate, unless described otherwise, above. Moreover, manymodifications can be made to adapt a particular situation or material tothe present teachings without departing from the essential scopethereof. Therefore, it is intended that the present teachings not belimited to the particular examples illustrated by the drawings anddescribed in the specification, but that the scope of the presentteachings will include any embodiments falling within the foregoingdescription.

What is claimed is:
 1. A bone anchor system comprising: a bone fastenerincluding a head and a shaft, the head having a first planar sidewallsurface, an opposed second planar sidewall surface, and an outer arcuatebearing surface extending between at least a portion of the first andsecond planar sidewall surfaces; a seat having a proximal end and adistal end, the proximal end including opposing arms extending along alongitudinal axis to form a U-shape, and the distal end including afirst bore formed about the longitudinal axis that receives the head ofthe bone fastener and a first coupling bore defined transverse to thelongitudinal axis through at least a portion of the distal end; and aninsert having a second bearing surface, the insert received within thefirst coupling bore to capture the bone fastener within the first bore,wherein the second bearing surface engages at least a portion of thearcuate bearing surface of the head and cooperates with the first boreof the seat to permit the bone fastener to articulate relative to theseat in a single plane.
 2. The bone anchor system of claim 1, furthercomprising: a second insert having a third bearing surface to engage thearcuate bearing surface of the head; and wherein the seat includes asecond coupling bore defined transverse to the longitudinal axis throughat least a second portion of the distal end to receive the secondinsert.
 3. The bone anchor system of claim 1, wherein: the first planarsidewall surface covers an entire first sidewall of the head of the bonefastener; and the second planar sidewall surface covers an entire secondsidewall of the head of the bone fastener.
 4. The bone anchor system ofclaim 1, wherein the first bore includes a first planar sidewall and anopposing second planar sidewall; and wherein the first planar sidewallsurface of the head of the bone fastener engages at least a portion ofthe first planar sidewall within the first bore, and the second planarsidewall surface of the head of the bone fastener engages at least aportion of the second planar sidewall within the first bore.
 5. The boneanchor system of claim 4, wherein the first coupling bore is formedthrough a portion of the first planar sidewall and the second planarsidewall of the seat.
 6. The bone anchor system of claim 1, furthercomprising a cap coupled to the head of the bone fastener and disposedwithin the first bore of the seat, the cap including an inferior surfaceshaped to distribute forces along the head of the bone fastener.
 7. Thebone anchor system of claim 6, wherein the cap includes a superiorsurface for receiving a connecting rod disposed within the U-shape ofthe seat.
 8. The bone anchor system of claim 7, wherein the superiorsurface includes a plurality of teeth.
 9. The bone anchor system ofclaim 6, wherein the cap includes a rectangular shape to be positionedwithin a rectangular portion of the first bore.
 10. The bone anchorsystem of claim 6, wherein the cap includes a circular shape to bepositioned within a circular portion of the first bore.
 11. The boneanchor system of claim 6, wherein the cap couples to the head of thebone fastener via an inferior surface, and the inferior surface includesa plurality of teeth.
 12. A uniplanar bone implant comprising: a bonefastener including a head and a shaft, the head including a first planarsurface opposite a second planar surface at least partially connectedvia an outer arcuate bearing surface; a saddle including opposing armscoupled to a distal portion with a central bore extending along alongitudinal axis, the opposing arms extending along a portion of thecentral bore in a proximal direction to form a U-shape recess to receivea connecting rod, the central bore formed to receive the head of thebone fastener and including a first coupling bore defined transverse tothe longitudinal axis; and a first insert received within the firstcoupling bore to capture the bone fastener within the central bore andcooperate with internal surfaces of the central bore to restrictmovement of the bone fastener relative to the saddle to articulation ina single plane, wherein a second bearing surface of the first insertengages at least a portion of the arcuate bearing surface of the head.13. The uniplanar bone implant of claim 12, further comprising: a secondinsert engaging the head of the bone fastener on an opposite side fromthe first insert; and wherein the saddle includes a second coupling boredefined transverse to the longitudinal axis through at least a secondportion of the distal portion to receive the second insert.
 14. Theuniplanar bone implant of claim 12, wherein: the first planar surfacecovers an entire first sidewall of the head of the bone fastener; andthe second planar surface covers an entire second sidewall of the headof the bone fastener.
 15. The uniplanar bone implant of claim 12,wherein the central bore includes a first planar sidewall and anopposing second planar sidewall; and wherein the first planar surface ofthe head of the bone fastener engages at least a portion of the firstplanar sidewall within the central bore, and the second planar surfaceof the head of the bone fastener engages at least a portion of thesecond planar sidewall within the central bore.
 16. The uniplanar boneimplant of claim 15, wherein the first coupling bore is formed through aportion of the first planar sidewall and the second planar sidewall ofthe saddle.
 17. The uniplanar bone implant of claim 12, furthercomprising a cap coupled to the head of the bone fastener and disposedwithin the central bore of the seat to distribute forces along the headof the bone fastener.
 18. A bone anchor system comprising: a bonefastener including a head and a shaft adapted to engage bone, the headhaving a first planar surface opposite a second planar surface and anouter arcuate bearing surface disposed between the first planar surfaceand the second planar surface; a connecting rod receiver having aproximal end and a distal end, the proximal end including opposing armsextending along a longitudinal axis to form a U-shape to receive aconnecting rod and the distal end including a central bore formed aboutthe longitudinal axis that receives the head of the bone fastener andincludes a first coupling bore defined transverse to the longitudinalaxis through at least a portion of the central bore; and an inserthaving a second bearing surface received within the first coupling boreto capture the bone fastener within the central bore with the secondbearing surface engaging at least a portion of the arcuate bearingsurface of the head to restrict movement of the bone fastener toarticulation in a single plane relative to the connecting rod receiver.19. The bone anchor system of claim 18, wherein: the first planarsurface covers an entire first sidewall of the head of the bonefastener; and the second planar surface covers an entire second sidewallof the head of the bone fastener.
 20. The bone anchor system of claim18, wherein the central bore includes a first planar sidewall and anopposing second planar sidewall; and wherein the first planar surface ofthe head of the bone fastener engages at least a portion of the firstplanar sidewall within the central bore, and the second planar surfaceof the head of the bone fastener engages at least a portion of thesecond planar sidewall within the central bore.